So what needs to be the focus? It seems most of the complaints revolve around content not the protocal, and how do you prevent low quality content or even outright spam/porn without putting some level of censorship in place? It also becomes a game of whack-a-mole. Those banned just create new accounts, how can you stop that without some central body collecting kyc and making the decision who is worthy?
If the issue is low quality clients or relays, then perhaps some sort of community rating system and allow for clients to autoblock based on those ratings, but that is still subject to manipulation (look at Google reviews). In the end you are responsible for your own feed and understand that you will most likely see content you would rather not.
My feed so far seems to be fairly "clean" it is a bit heavy on Bitcoin topics but that is to be expected, outright spam does not bother me all that much, and any porn gets blocked as I see it.
There is also nothing to stop anyone from forming there own walled off community that does implement strict censorship, create there own relay that autoblocks, restrict clients, inspect follow lists, go crazy, but that is not a "nostr" the protocal issue.