>So I’d appreciate any honest input: what kind of features, format, or community structure do you think would make a site ACTUALLY worth visiting, aside from nekos?

it's not easy to make something that'll last a long time and a lot of it is about being in the right place at the right time but you will benefit by choosing a format that hasn't been used much on the western web so theres a reason to use it.

Theres a huge amount of untranslated japanese scripts out there

the one trade-off though is that Japan is the land of the rising masochists and have the worst mod tools ever

so you should learn how 2 code and how to code in perl if you dont already.