Well, I would have a problem with this. A lot of times, I (as a max wizard) or another one of my lower wizards, agree to help one of my mates with a dungeon. Often, it will only be us two at the sigil, and I'll try to go to Team Up to get some more help, say in long and more higher leveled dungeons. On occasion, there will have all ready been too many people in the Team Up, and I am transported in there without the friend I was originally trying to help, so I apologize to the team and leave.
I wouldn't want to have to go through an hour's wait just to try again for at least a team of three in Mirror Lake or something, especially if I'm on my transcended wizard!