Being a centralized storage provider does not improve your ability to moderate illegal content, funding does.

Relays making tons of money should certainly provide them with the funding to prune illegal content like nostr.build does. 

Many new AI tools are growing for this very purpose. These will only proliferate over the next decade.

Although, I agree that not all relays should be forced to host files — only the relays capable of sustaining it. Everything is modular and voluntary, but we cannot rely on the centralized web forever!