I would argue the Kama Sutra is both historical and educational and not sexually explicit at all. Perhaps a celebration of human bodies even, I don't know.
It seems though that Apple particularly feel that its customers require a squeaky clean filter to assess everything they access.
For cloned and low quality app's this is great! Restricting porn... I guess it is a good thing. Kid's can browse the app store. However this grey area between what is clean and what isn't is something they have never mastered.
It is really sad to see Google following this path of over-censorship..