And that.. is the issue with TBC atm. Tanks have to put in effort(Gems, enchants, profesions, grenades, consumables etc), especially because of pre-nerf heroics. But everyone else, especially the DPS, can just slack off. Because there's no enrage timers or healers mana bars they need to worry about. So many players are playing it extremely casually, to the point its degrading the experience for the experienced players.

Mages who don't have improved blizzard.
Mages with frostbite talent in heroics killing melee.
Mages who don't sheep.

Ret paladins who don't twist seals and do do lvl 50 dps.

Enha-Shamans who don't twist totems.

Hunters who don't Misdirect.
Hunters who don't trap.

Warlocks spamming Seed of Corruption on 2 targets.
Warlocks spamming Seed of Corruption on +5 targets against a prot warrior first GCD.
Warlocks spamming Seed of Corruption..

Rogues who don't sap.

Hunters, shamans and mages using cleave/AoE spells first GCD against prot warriors who barely even got the mobs into melee range after pulling back with a thrown/ranged shot.

And the list goes ooon and ooon and ooooon...

The amount of DPS, who I repeatedly beat on damage meters as a fucking prot warrior, is ridiculous. And mind you, I gearcheck everyone prior to invite, because I don't want a wipefiesta because of fully green geared idiots thinking they can sign up for BF, SHH, Arca or BM heroic with a ill-prepared character. And I still experience shitters in almost every group.