Maybe because it's not in your face boobs, or over sexualized art.

Sometimes, calm simply art can be more attractive to our eyes because the point of the art wasn't to come out as sexy.

That or because we can see her thighs. It could be that.

Why is it that this is so much more attractive to me than any other NSFW art on this site. Maybe I've just seen too much and I appreciate the simplism more now. Who needs balloon tits when you can stuff like this?