It depends what you want to do. If it's shit posting relays seem fine. If you're trying to reliably DM to reach a friend relying on a volunteer army of relays might be a bad time.
Nostr DMs do suck. For nostr what would improve it: strict time limited FIFO style relays that only allow you to store messages of a certain size for a week or so. Then your "home relay" or "main relay" retains whatever you want it to. I believe hodlbod experimented with it but not sure how it worked out.
For keet/iroh: the main thing that would improve it would be just running your own "home client" that is always on (a la Start9/Umbrel). That eliminates the problem of "hoping the group chat host's phone stays online". That's not realistic. But a home server mostly staying up, mirroring to his phone and sharing state with the other participants is realistic.
