I was a DK tank up until lategame cataclysm, and I really only had to run in and spam ONE macro. ONE. On every single fight. In turn, no DPS could ever pull aggro off me, outside of insane gear differences early in an expansion cycle. My positioning was trivial, aggro was guaranteed higher, and there was barely any decision making outside of actual raidbosses involved.

So far in this game, mind you I am only PLD lvl 33, there is a huge difference in how easy it is to gain, keep, and develop aggro, based on a number of variables, not the least being DPS behaviour. For example, positioning is not trivial, as its easy to lose aggro on a secondary mob to an overnuking DPS, and the mob moving in a direction which forces me to run after it, in turn making me liable to lose aggro on other mobs. Also, I cannot just use all my skills as time and GCDs are precious, and I have to maximize threat before starting to lay on dots etc.
We are still talking about single-group dungeon content, right?