The dust has settled on most of the servers, and the Fury of the Sunwell has been a success across the board. One of the lingering issues however is attunement. It has been noted before that Onyxia is now the hardest attunement in the game. This has occurred with the removal of the Karazhan, Black Temple, and Mount Hyjal attunements. However this creates a false impression that these instances are no longer worthy of attunements, and thus these quests are no longer worthy of the care and time that's necessary to push forward into them.

You want to get your Vashj and Kael vials, you want to complete your Mount Hyjal attunement, and you want to complete your Black Temple attunement. If you're in a guild that isn't running those instances anymore and is focusing squarely on the Tier 6 content, then you still want to go back and get the attunements.

Why?

I'm glad you asked.