I feel that we, as a society, should try to apply this idea in a lot of areas..

Isn't viewing child porn also a thoughtcrime? Obviously this would apply only to viewing it and not creating it.

If I am not mistaken Japan illegalised viewing CP in ~2009 but distributing it was illegal beforehand.

That's one factor, the other is the culture around youth appeal through drawings. Mangas were filled with teenage erotism. So lolicon is not a huge stretch from there.