I'd really like to see a fix for dungeons that have multiple parts. Specifically Aquila. There are hidden bosses and really all I need to do is pair up with some people who want to do just that part -- but the "join teams" doesn't give me that option. Then we get in there and I'm paired up with people who want to do the whole dungeon, which I've already done. It would definitely be a nice change to see join team for hades or join team for cronus, etc.
This would be a very helpful option for people who just want to do the "extra" bosses and not the entire dungeon, I agree. I would love the option to team up to do one of the extra bosses - that way I wouldn't need to use crowns minions.