If it's only afks it'll be incredibly useless, as those people will find ways to abuse it. (Hey lets make a macro that casts a spell every 10 mins!)

People keep talking how vote to kick would be awful and constantly abused, yet at the same time the forums are full with threads about abusive players, afkers, trolls and so on, exactly the kind of behaviour that vote to kick can take care off.

I've said it before and I'll say it again. Trolling is a lot easier when one person can mess the run up for the entire group rather than when you need a group to troll a single person.