I had some time to think about this. And from what I gather, the missing encryption is probably one of the major showstoppers here.

For one people expect chat to come with some minimum standards. I mean proper e2ee and several other features have been part of practically every other chat solution out there, for quite some time now. And we need it to supply that amount of confidence to enable people to talk to their family, friends, colleagues... We'd need it to eat our own dogfood and discuss internal stuff within mod teams, etc...

And semi-public unencrypted chat messages are kind of a liability to admins as well. We expect people to do nefarious stuff once they think they're in some sort of closed group. And that stuff can't federate uncontrollably and we also can't have it sit on our servers. And that means either encryption as well (so the admins don't have to deal with it). Or a massive amount of effort and potential legal issues.