This has probably been suggested, but after a string of PUG's with people that just zoned in and stood there while we did the quest, I felt the need to say SOMETHING.
I know that you do not want to have one person with the ability to just boot someone out. How about the group doing it though?
I feel that this would help address the issue of people piking their way through the levels, along with other issues. I've had someone say they had to go while running Tangleroot, exit the quest when we were done, but stay in the explorer area. This prevented us from removing him from the group and inviting someone else to complete the quest series. I know all we had to do was go out into the tavern and disband, but honestly... sometimes it is difficult enough to get a group of people to just GET to the quest without explaining we now have to all recall, reform and go back out.
Maybe to help prevent abuse, the vote would have to either be a majority, or minimum 4 people. Once the vote passes, there could be a timer for the person to be removed. This would help prevent griefing I would imagine.
I'm sure this has been suggested somewhere, I just didn't have the time to search through and bump the thread, so here's someone else saying, Give us an option to boot! Why should these people be rewarded for our work?