Actually.
Some of those people did have legit complaints about some of the game mechanics, and the PvP forums are still full of rage, and with good reason.
In all honesty negative feedback is still positive feedback. If everyone just "Went with it", especially in an MMO, the dev's would assume everyone was happy and nothing would get fixed or improved upon.
The reason things have died down here has less to do with the fact that the community is booming with new enthusiastic subscribers and more with the fact that you can't post on the forums unless you have an active subscription, and most of the people you described have probably canceled their subs.
I doubt if people wanted to stop playing the game, they'd continue to give Bioware money just so they could go on the forums and complain.
But, at the time they were here, they were still paying customers and had every right to express their views on the game and how they disliked it, just as you have every right to express your views on the game and how you DO like it.