You want to know why RVD stayed in the company even when he didn't want to? Money. It drives his need to wrestle. Pot doesn't come free, and there was no other place in the world that would pay him that much money. He quit because he knew he was stable enough, at least for the next few years, to not need to work for WWE when he don't want to.
And the "You wouldn't know what's going on backstage so stop hating HHH" line is used so much it's not even funny. We all know that HHH probably thinks just because he shagged the owner's daughter he gets more rights than normal. You can choose to live in denial, or you can accept the fact. Maybe RVD stretches the fact a little, but when it comes down to it, when HHH doesn't like you, your career is doomed.
And RVD not being cheered, he was getting more crowd reaction than Edge and Cena at the time he was champion, so I don't think any argument is valid. It gave Raw something fresh, and the crowd was more receptive than it ever been since.
True, ECW was not the ECW it once was, and Vince is trying to attract the WWE crowd, not the original ECW crowd, so whatever RVD said wouldn't have made a difference. Afterall, he was nothing more than just a wrestler.