I only mention Roll play for what players do mostly in Casual servers. Of course there is way more you can do. As if there is no exit in the a level, You can make up your very own games if you have one hell of a imagination if you choose to. You can host certain wads that you can not host in standard servers. (This does not mean its only a Roll play and Hangout wads) You can do many things without the rules limiting you down.
As for the whole room ordeal, honestly it works as is. Why fix something that ain't broken. Sure there are ideas that can improve it. but honestly, who on earth is gonna switch the rooms for different gametype servers? I mean you can see the gametypes all in one place. With little to no issues to differ one or the other.