Heheh, the reasoning is simply this: I don't like seeing nipples and genitalia (for the most part).
I believe I COULD make nipples that I'd like seeing, but it'd be a lot of extra work for (to me) little payoff.
There's a middle ground between ecchi anime and hentai that turns me on the most, that I can never seem to find anywhere online. Since I can't find it, I decided to create it.