Trash favors AoE damage.
Chain-pulling favors high regen/efficiency.
Guess what? Tanks are all about AoE and we're designed to not run out of mana/rage/runes: we have constant regen, or in the case of non-DKs, boosted regen based on incoming attacks and damage taken.
We're an AoE which never has to worry about too much aggro or bursting too soon. We get reactive damage that DPS won't see.
Besides, they're trash meters. Who gives a shit about trash? But if you really want to be classy, do it in a leveling instance.
Last time I played with such an arrogant tank I'd been on my paladin.
P.S. Don't stand in the whirlwind and puddles.