

Your reasoning would hold up if 80% of xmpp wasn’t running on Conversations or forks of it, that all support OMEMO and OpenPGP.
Your criticisms are too broad with few serious negatives. What makes extensions powerful is that they can easily change the rules without breaking the underlying system. If your client sucks, get another?
You have choices, but if your problem is metadata, whoooo boy.
https://news.ycombinator.com/item?id=32780665
https://github.com/matrix-org/synapse/issues/9133
https://www.reddit.com/r/PrivacyGuides/comments/q7qsty/is_matrix_still_a_metadata_disaster/
That’s their problem. If their messages aren’t encrypted, it isn’t like you won’t be aware of it. Request that they use a modern client and get with the times. None of this is an actual problem without easy solutions.