I think customer feedback can make a difference whether it is in forums or reviews or blog posts or where ever, V8Beast. I can give you another example. I think of Syl Arena's blog post several years back on Canon's Speedlite system. It resonated with people and Canon let him know they had read the post and was monitoring the responses. Several years later a vastly improved new flash system update is introduced that closely conforms to Syl's original wishlist. I'm not saying that Syl spec'd the new system but Syl's post and the big response helped crystallize and confirm what users were looking for.
I agree that listening to all feedback is important, but like all companies Canon has to weed out the fanatics from the serious users. Translation: all feedback is welcome, but feedback from people who are willing to spend the money and contribute to a company's quarterly earnings are much more important. On the internet, you get people that talk a lot of trash, but don't put their money where there mouths are 
Actually forum posters seem to have more high end stuff, more money put into it, than the average user from what I see. You see a lot more talk of people owning super-tele, T&S, fast L primes, etc. on forums.
I've said it before and I'll say it again. Many hobbyists I see online have nicer gear than a lot of pros I work with. This makes sense, as photography is rarely a lucrative profession
You can get by and make a decent living, but I don't know many wealthy pro photographers, and that has nothing to do with talent.
Yes and the collapse of newspapers and magazines has made the PJ job fortunes meeker than ever. Some salary figures I've seen recently have been really scary (so scary they kinda scared me back into my original game plan for a living). The sort where a grad student might look like Donald Trump in comparison.

That said, these forum posters that you speak of with all this money, how much of the market do you think they represent? I'd venture to say it's quite small.
Probably not a lot compared to all of the rebel and some of the xxD users.
Likewise, what do you figure the ratio is of whiners vs. people that actually went out a purchased the gear they debated about online? Me thinks the ratio favors the whiners by a substantial margin, because if people put their money where their mouths and bought new gear, they'd be out shooting with it instead of perpetuating the online whine fest.
I don't think so. The whiners seem to have a lot of equipment on average, although I have hardly done a careful tally. I can say that I myself have a super-tele, some L zooms and medium and short primes, two bodies, TCs, etc. etc.
And some of the AF whiners have insane equipment sets with super-tele galore. (the 5D3 and 1DX may quiet this group right up, the 1D4 already did to some decent extent and even the 1D3 after the fixes to a lesser and hardly universal extent and the 7D to some extent among the more amateur and more forgiving of that set, Canon may have finally answered the loud cries of this set)
Out of curiosity, do the words "14 stops of DR, bey-otch!" or "DxO rating of 95, recognize mofos!" appear anywhere on Nikon's marketing literature for the D800? You'd think that if it was such a big deal and such a great marketing tool, Nikon would be taking advantage of it.
They do appear in some of Sony's.

They definitely brag on the Exmor DR.
Nikon may have been wary to play up DR too much in press since their flagship D3s and D4 have less DR than some of their consumer APS-C and their D800 and the heavily Sony-aided sensors outdo the ones they made without much Sony help.
And anyway DxO and all do it for them.
To be honest I don't know what they drum up since I haven't looked at Nikon marketing too much (other than all of the Ashton commercials on TV for point and shoots which can't be avoided).
Anyway most of the 5D3 they did get right.
The low ISO stuff is a bit lame after 5 years and all the bragging they did about how they are so far ahead they don't even need to try. I just hope they take DR seriously for the 5D4 round.
The grass isn't entire green on Nikon's side so I will stick around for the 5D3 it does fix a lot of body performance stuff I had been hoping would get fixed for years with the 5D series.
That said if the sensor is way behind again 5D4/D900 round I'd sadly have to decide to switch to Nikon after years and years of Canon shooting.
I seriously thought about for the first time this time, but it doesn't quite make sense to switch yet, taking ALL about the 5D3 and other factors such as $ and lenses and UI and video into account, but if the are left in the dust for dynamic range and such next time, I'm afraid it will be a switch (and with canon lenses becoming more expensive and my super-tele getting old, etc. it might not be that much of a $ factor to switch by then either).
And you have to admit Canon has become the king of silly little crippling's of their bodies, more than any of the other makers at this point in time. Although they finally stopped crippling AF in a big way this time at least. That was awesome.
I do know so more purely landscape guys who are switching to Nikon now and might not have had the 5D3 simply had even just D4-levels of dynamic range, MP left at 22 as is. (Of course I do know a few Nikon landscape guys who couldn't afford the superior D3x and nabbed a 5D2 the last round)