Sex is an appetite, just like hunger or sleep. It's healthy and natural to satisfy this appetite. There is nothing wrong with satisfying sexual urges, just like it would be madness to not eat or sleep, we have these urges for a reason and they evolved because they were good for us.
Obviously, any appetite can be abused. If you eat too much, you get fat. And if you have casual sex, you'll get emotionally scarred and physically disease-ridden. You'll also end up getting pregnant and having to support unwanted children, whether as the woman or as the man the child support is going to be an extremely heavy price to pay for a stupid petty orgasm. So yes, sex is not some mindless activity we should fling ourselves into at all moments. But that doesn't mean that satisfying your sexual appetites within reasonable, harmless bounds is the same as being a sex crazed lunatic.
Which brings me to erotic content. Content designed to satisfy people's appetites in a way that's harmless and pleasant, with no bad consequences or after effects. I have no idea why people object to this type of material. It seems like an unadulterated good and a perfect replacement for sex with actual living people, which is the cause of all the bad side effects listed above.
Erotic content comes in all shapes and sizes, but the goal is basically the same, to satisfy the appetite so that it goes away and you can again focus on other things. It shouldn't take any longer than a normal meal, and represents no burden on your day to day living. It's also free, and it leaves your brain completely unaddled after the fact, so unlike drugs, alcohol, cigarettes or gambling, no one can complain about the impact it has on your daily function.
There is no evidence that viewing things in a fictional universe eventually leads people to do them in the real world. Endless video game and movie studies have already proven, endless times, that sentient people can tell the difference between reality and fiction. Erotic content of any type is entirely harmless, and has not been shown to be harmful in any way, shape or form to anyone. in fact, given the number of times it forestalls casual sex, which is an actual danger to people's lives, I would consider it one of the healthiest objects on Earth. Sort of like how diet milk shakes are a great improvement over pig lard, even though they both include calories, and those who settle for the diet milk shakes end up much thinner than the ones who insist on sticking with the pig lard because it's 'natural and normal.'
The best erotic content can replace not only the appetite for sex but also for relationships. With romance stories between fictional characters, you can have a fantasy relationship with an actually worthwhile girl who A) won't get pregnant and demand child support B) costs nothing to date C) will never cheat on you or dump you D) is ten times as beautiful as any living woman E) is far more willing to actually have sex with you or go on dates with you or even hold your hand F) Is far more loving than people's feelings ever realistically reach in the real world. G) You can cheat on with endless additional fictional girlfriends and she'll never know and never get upset, thus creating a world of endless variety. If a story works hard to establish a wonderful girl who has wonderful feelings for you and then you get to have wonderful sex together, what more could you ask for? And if you've already reached the first two aspects in said story, is there any real reason to refrain from including the third aspect? Does it somehow improve the romance to leave out the best part?
But erotic content is so varied a term that it even covers just soft aspects of appreciating the female form. To me, there is nothing more beautiful in the universe than the female body. Obviously, a cadavar just sitting around somewhere isn't very attractive. But when that cadavar takes on a soul, has a bright expression on her face, a graceful active position that clearly only a feeling thinking soul could normally reach, is dressed in clothing that most brings out and suits her personality, is featured in an environment that suits her, or among friends she cares about, or whatever -- it turns out that everything else in the universe serves to make the female form far more beautiful than the female cadavar. And when you feature the female form in anything, doing anything, it enhances the beauty of both the woman and her surroundings to an endless level. I don't think there's really an end to female beauty. There are so many varieties of women, and they can have so many different stories of both where they came from, who they are, and where they are going, that I just don't think beauty has a stopping point. There's always something attractive left to draw that still hasn't been shown before. Sort of like how the number of beautiful musical melodies still hasn't dried up after all these centuries, and we're still composing new songs to this day. Every single time a bit of eros is included into our other products, those products tend to be improved. Because female beauty is beautiful, captivating, and perfect. I could not ask for more from any product, of any type, than to also have a bit of attention paid to the beauty of the female form as well. Even football games have cheerleaders on the side. Why is this? Because female beauty is always good. In everything. Everywhere.
Eros is why we appreciate the female form. The wish to have sex with said girl is the root of our appreciation for her face, figure, hair, dress, everything about her. Denying eroticism denies our ability to appreciate virtually any good thing left in life. Even song and dance is tied back to wanting to have sex with said singing or dancing woman. Beauty is the sexual appetite, and the sexual appetite is our aesthetic sense.
I do admit that there are times when erotic content is inappropriate and out of place. It disrupts the story and the characters, it feels unrealistic or just a waste of time. It can even cheapen things by making it all too easy and predictable. These are stylistic objections, however. They are not innate and they are not moral objections. If done well, any erotic content producer can find a way around these objections and introduce eros into any story they please, and it will always become better as a result, because eros is a good thing, one of the pleasures of this world, and a story that encompasses a greater breadth of the world's good things is by definition itself a better thing than a story that encompasses a smaller portion of the world's good things.
All the best anime, all the best manga, all the best light novels and all the best visual novels have heavy doses of erotic content in them. Some go further than others -- like Shukufuku no Campanella or To Love-ru, but they all have some, because all good art realizes the need for eros as an element of the pleasure it's trying to convey to the audience. Series that specialize in eroticism because that's where they've found their groove, what they're best at, and what they excel at in terms of reaching their audience, are in no ways inferior to, say, players who play Vega in Street Fighter as opposed to any of their other choices. So long as the story is good, by definition their decision wasn't wrong, it just so happens to be their playstyle to include more erotic content than average. If you win with Vega then by all means keep playing Vega. It doesn't matter what other people do or how they succeed. It doesn't matter whether it's possible to win at Street Fighter without playing Vega. It isn't just suddenly morally wrong to play Vega on principle, and therefore to be avoided if at all possible. Since there was nothing wrong with choosing Vega in the first place, it doesn't matter in the least whether choosing Vega was really the optimal choice for all people at all times in all places.
If you're especially good at satisfying people's sexual appetites, that makes you just as good as a prize chef in a 5 star restaurant. I think the artists behind To Love-ru and Mujaki no Rakuen are amazing. Many other people agree with me, which is why they sell so well. This isn't something to be ashamed of, but to be praised for. These people have uniquely great skills and they're providing a uniquely valuable service that is making a great many people happy. Many good stories are good precisely because of their focus on erotic content, not despite it. These stories don't have to be apologized for. You don't have to be ashamed of liking them. Eros is a great pillar of this world and humanity, just like any other pillar you could point to. Generally, the best authors tend to have a softer approach to erotic content, like One Piece and Fairy Tail, that just as a sidenote are constantly showing off delightful female flesh while also telling their serious plot-driven stories. But again, just because the best player of Street Fighter plays Akuma (hypothetically speaking), doesn't mean everyone is at their strongest when playing Akuma. There is more variety between people in this world than that. Furthermore, if there already is a perfect One Piece in this world, there's no point making a clone of it. Instead, a Futari Ecchi which in no way overlaps with One Piece, but instead does a great job covering a subject One Piece doesn't, actually better enriches the world than One Piece #10,000,000 would.
I am sick and tired of people objecting to stories with erotic content on the basis that they have erotic content. That somehow SAO becomes bad because it has a low-angle shot. Or Fairy Tail is bad because Lucy is stripped yet again. Or Haruhi Suzumiya is bad because they dress up in bunny suits. or Code Geass is bad because Euphemia and Kallen are found nude on the deserted island. So on and so forth. In the end every good series is disqualified by the god damn prudes who are so intent on denying the beauty of the female body that no story about anything anywhere gets through their censors. If for some reason your brain has totally haywired and you no longer have any sexual appetites, if the female form disgusts you and you would rather be blind than look at curvaceous women, then too bad -- keep it to yourself. You have no right to impose that warped, twisted view on all the rest of us who are enjoying a bit of harmless fun satisfying our erotic needs. Eros exists. Get over it! Satisfying it is perfectly healthy, natural and normal. The tools to do so are in no way to blame, evil, or wrong for doing so. There is nothing wrong with any portion of the entire framework.
And no, it does not harm children. Japan is saturated with this stuff, and has the lowest crime rate and the least sex in the world. So no. Just don't even start with that shit.