They've already tried to get people to tank more. Bigger rewards, special mounts. What else can they do to get people to try tanking? Automatic weapon drops everytime they do a dungeon? A complete set of gear for that dungeon? That's not fair to the other roles. And I say this as someone who's currently maining a tank role.

Is my suggestion perfect? No. I'll admit that. But I don't see how it'd make it worse. A group will move a little faster while another group will be pretty much the same.

I would like to see five party dungeons, but the content from 2.0 to current would be way too easy with that. Not with a complete dungeon overhaul. Otherwise, it won't be fun. Even then, I'm not sure they could. The 8 member party dungeons at the end of ARR was too easy.