The same thing happens if you lose your password, so that's not really any different.

As for the public key issue, just like I mentioned initially, the metadata is being exposed, but again, is that such big of a problem? It's like having your followers list set to public instead of private. I personally don't think that's such a big issue.

Furthermore, there is currently some progress being made in this direction in trying to anonymize this data as well. So even this last hurdle could be fixed.

I still think Nostr DMs are a better solution overall than either Simplex or Keet. Both of which lack the option of sharing the chat between multiple devices (as chats are not long lived on a server) and the overall UX is horrendous (for Simplex you need to start a conversation with the other person while being physically in the same place, since you don't have a long lived unique identifier).