All three of your points on usability are definitely true, especially #3. I haven’t been able to find a good TUI client.
Regarding the technical points, it seems like there are mechanisms to address each of them. Please tell me if I’m wrong on any one of these. I have only been learning about Nostr for a short time.
Relays aren’t a single point of failure because a user can (and should) post to many of them. The attacker in a censorship or sabotage scenario would have to take down every one of your relays at once. If they were taken down gradually, you could replace the bad relay with a new one and advertise that one on all the other relays your followers already use. It’s much more resilient compared to twtxt.
Every event contains a signature from your private key, so it’s hard to spoof. NIP-10 provides a method for marking a note as a reply to another note.