It's a given in human nature, and made worse via internet anonymity, that few will accept and explain what they did wrong, instead focusing on the other person and how they can shift blame.

In general, even before the threat changes, if you focus what the tank is focusing, and AE what the tank is AEing, you shouldn't have a problem (Wrath on at least). The problem really is more of when you focus fire on an off target, where the tank has only hit it with tertiary powers.

Controlling your own threat is on you, but tanks play a role also, obviously. It's hard for anyone to gauge their power level accurately at times. I see many tanks that are undergeared but think they can chain pull like they're decked in epics. Just this past dungeon I had a "gogogo" healer, when the tank died his comment wasn't "sorry, got ahead of myself" it was "tank you need to use your cooldowns better".

There was also a shift in Wrath that kept up in Cata, that tanks don't so much "pull" as they "charge". Not just warriors/bears, but all tanks will run to the position of the mobs, rather than pulling the mobs into a position that is optimal. Don't tank stuff in the middle of CC'd mobs!