I support this. It would be nice to have some better/fun leveling options. I would like to get a couple crafts and a gathering class to 50, but it's such a tedious process at the moment.

This idea has actually been brought up before, and even the idea of combined instance dungeons. It would be nice to see a dungeon designed to have say, four battle classes to clear mobs, keep mobs in their place, etc. and then a couple crafters and gatherers grabbing items and crafting to sort through dungeon puzzles. Of course because of people having multiple 50s I think a "class lock" for the instance would help to keep the challenge in place.

Of course all these ideas need to be fleshed out a bit more, but I think the premise of this is a great idea.