I definitely like the idea of learning a new dungeon with a group of random people but it's just not realistic for a dungeon/boss that's been available for a while.

Cape Westwind is the perfect example. Nobody runs it except people who are new to it but just need it to advance the story. Result is insane wait times.

Practice mode would turn out the same way.

Your best hope is to hit DF when a new dungeon is first released and then everyone will be derping for a few days until people start memorizing it to the grind.