No, this is pretty common for Japanese guys. The whole island pretty much has a fetish for any part of a girl they normally wouldn't see/be allowed to touch, with tits often pretty low on the list.
this image isnt poorly drawn, dont add images to the why was this approved? pool just because it doesnt suit your interests of naked women rubbing each other
It's not about "poor quality" it's about bad images like shit hentai which Danbooru is full of and needs to get rid, which brings the question of why they were approved.
Just because YOU don't like it, doesn't mean it needs to be deleted. After all various people like various things and you should learn to cope with it. Also I would like to know what your definition of "shit hentai" is. And obviously those bad pictures you don't like were approved of because some mod who apparently doesn't share your tastes decided so.
Would you like it if mods approved shit like amputee dick nipples getting fucked by a fat man? It's called keep it in /d/. There's a reason why there's a site like that. Sure someone may like it, but not everyone enjoys everyones fetishes. Danbooru isn't /d/, images on here should be good art like Usatarou, not grotesque or "quality". Maybe Danbooru needs the opposite of Safebooru where the Alternative hentai goes so it can stay away from here, but I'm probably alone on this thought. ¬¬;
I don't like amputee oder dick nipple pics either but there is a blacklist and I make use of it. Just do the same as me and put the tags you don't approve of on this list. If I were you, my problem would be solved with this. Hell, i've blacklisted touhou and vocaloid because I don't like. And don't forget isn't 4chan either, there is no /d/ here and thus no possible way to "keep it in /d/". And yes, I do like some grotesque pieces of art and I do like some completely SFW things and I do like that there is one site for everything I like.