I see the need of a default channel (or many) as new users need a place to land automatically be connected to some company channels. Perhaps the feature will be to have a fixed default (town-square) that can be renamed by the admin. And then let the admin pick other default channels (like Off-Topic).
Particularly, we have 4 "channels" that we want everybody to be (and that's besides the 2 defaults of mattermost) So right now I have to tell everybody "Ok, now join
Technical Service, etc".
Having the ability to configure the default channels will be great.
I don't think we can't get away from a "town-square" channel where every user is a member (with no choice to leave) as that will be the only way to reach all users in the team. But it will be nice if it can be renamed.