>>31570175It's a combination of things. Anime obviously designs women of all ages to look very attractive.
Partly it's because paedophilia and beauty are considered slightly less taboo there (although the age of consent being 12 like people say isn't actually true)
Partly it's a more extreme version of how western media tend to pick attractive actors, even if they're not necessarily meant to be sexy. People just find attractive people more pleasant to look at and enjoy shows more if they are.