Have you ever just read/seen a visual novel that was really great, but it was 18+?
Yeah, I've been there many of times. It's not just Saya No Uta either, it's also Katawa Shoujo, Kara No Shoujo, and Gore Screaming Show.

It's like, why can't they make an anime out of these visual novels and leave out the dirty bits? That would be sweet, but sadly, I don't see it happening. :C