Customers get angry because of broken promises? Heck, after following the 4e launch, you´ve had to realize that some people just get angry about anything.
And sometimes, the "internet rage" or "nerd rage" or whatever dismissive term is used, is simply someone airing a grievance because they're disappointed in something they were told that is no longer the case. Sometimes it's just a way for the opposite side of a discussion to belittle folks backhandedly, by saying that they shouldn't be mad, because what they were told wasn't really a "promise", so they shouldn't have had expectations to be spoiled.
Honestly, this thread is just sad. The OP tries to inject some perspective into a heated discussen, and suddenly the usual suspecs pop up and gleefully use the opportunity for finger-pointing and fist-shaking. The realities of the publishing industry? Reacting to market changes? Changing your plans when you realize that some things are just not working out? BUT WE WERE TOLD....
Oh well, internet.
The thing is, you've got to recognize both sides of this. If someone says "Man, barbarians are out? WotC promised us barbarians." They're simply expressing their disappointment of the lack of barbarians and their disappointment that the company didn't deliver what they were told.
Projecting a sense of entitlement onto them may make it easier to discard their opinions as "WotC didn't promise anything, get over it", but that doesn't address that the barbarian is missing.
It's the old joke about telling a cop to leave you alone, because you pay his salary. I don't see that from the postings, I just see disappointment that things are not as they said they were.
It's one of the things that soured me on Paizo, when they utterly failed with AoW Overload, and the rabid fans went after everyone that questioned it with "well, it's a free supplement, so shut up!". It doesn't address the issue of lacking the material that was supposed to be there.