What's the big deal? They cleared the instances on beta already, so it's just a matter of levelling fast. It's not like rogues tanked Illidan in TBC or anything, oh wait ...
All the people with their knickers in a twist about this should really understand they're the ones being too obsessed with this game not this high end guild. They're enjoying the game the way they want to do it, more than I can say for the people whining about them.
It's a nice achievement for them and people should back off.