I love playing lobbies, especially when everyone is in mumble. When I create a lobby, i set mumble required, and ask the power classes ingame to join mumble. Still, that usually doesnt help, and we end up sitting in mumble with 3 players, so calls are basically useless, and its almost like playing a pub.
I wished you could select an option, which makes mumble 100% necessary, and everyone who doesnt join, will be kicked automatically after 3 minutes of being 'afk'.