If you prefer FluffyChat's UI over Element's then I'm guessing you are after a 1:1 or group style chat (i.e. chat bubbles), similar to say Signal or Facebook Messenger. Element isn't catering to this audience from what I can tell, it has a UI that is similar to Slack or Discord, which is suited for large group chats. Just because you aren't using Element in this way doesn't mean that it has the "worst UX" of any other client.
Your third point is a client side feature. If you meant that you want Element to have that feature, then yes I agree. But in saying that, it wouldn't surprise me that it's not high on the priority list when most clients (of any chat app) have this feature.
Your third point is a client side feature. If you meant that you want Element to have that feature, then yes I agree. But in saying that, it wouldn't surprise me that it's not high on the priority list when most clients (of any chat app) have this feature.