I supposed they don't feel very confident about the UI. When I looked at the Nightly a couple of weeks ago, the UI experience inside tha Matrix features was horrible. I hope this has been fixed/will be fixed soon.

I downloaded Thunderbird just to play with Matrix integration, and I think this is the right answer. The rest of the UI looks much more refreshed and new, and the Matrix window feels a lot closer to older IRC apps than anything else. Not that it's a problem, just an observation, but I would prefer it looks a little newer and fresher, personally.

Does the 'chat' space in the sidebar glow/flash/gain a number when you have an unread message that needs your attention?