Early on in ARR, there were dungeons where it was quite possible to overpull for the average player or maybe even the above average player. Looking at you, Brayflox and Brayflox (Hard). The problem with that was that many healers couldn't handle it. Or they just weren't used to it. So, you actually had to waste time at the beginning of a dungeon asking the healer if they could handle wall-to-wall. And then there'd be griping if it failed.

In my opinion, many players steered away from healers and (to a lesser extent) tanks because of this. SE "fixed it" by pretty much making nearly every dungeon since be two pulls and then a wall. And they've followed that formula since. Apparently we aren't able to decide for ourselves how much is too much.