As I already said: 2700 is a lot on its own, but it doesn't matter how many players you poll if those players are not a cross-section of the entire game population. Thus my example about the political rally - you can poll every single person in attendance about their preferred political party, and gather far more responses than you would need for a reliable random sample, but if your sample isn't random then no sheer number of responses will make it an accurate representation of the whole population.
You're assuming here that hardcore players' opinion of how the jobs should work is the best one that would be appreciated by everyone. It isn't, necessarily.
Case in point (which has already been raised in this thread just above) is healer complexity. It's a constant complaint here that only having one attack button is terrible and boring.
Personally, coming from console games mostly, one attack button is normal. Having a one-two-three combo spread across three buttons is needlessly wasteful of buttons, and the overall number of skills is immense. I'd rather have less skills than more, and have the complexity come from the game environment or the fight. Also I know for a fact that I tend to "tunnel-vision" when following a DPS rotation, and and making healers do that would be a surefire way to make me do a terrible job of either healing, DPSing, or both. (I do miss Aero 3 though.)
Is my opinion common? I don't know. But increasing the complexity level to suit the small number of people asking for it might have a negative effect on job satisfaction for others. People who are happy with the current gameplay are inherently not going to be complaining about it.
Edit to add: The "one button is boring" complaints also overlook the fact that you are doing that while monitoring your party's status and breaking to cast healing spells when needed. One mindless skill is exactly what I want when my mind is on other things.
I'm not saying the poll is as biased as that hypothetical one would be. Just an extreme example of why "we polled a large number of people" doesn't guarantee that the result means anything if you didn't poll the right selection of people.
Also, while it's not really relevant to the example either way, voting is compulsory in some countries.