Dear Mike & Monte,
As you work on the next iteration of the game, please do the same thing that all the previous game creators did on their specific edition:
Make a game you think is fun.
If it is, then many other people will end up agreeing with you and buying the thing. But don't worry about any of the specifics you see here, on your own boards, on RPG.net or wherever else you might look. Because there is not a single thing you will put in your new book that someone, somewhere will not bitch about. We're going to complain about everything. So just do what you feel is right, and know that some people will appreciate it.
I agree with your sentiment here but think the last paragraph is an over-simplification. First of all, it isn't
either you try to every single demand please everyone
or you ignore any input and just make a game that's fun to you. You can do both (in fact, I'm sure that they are doing both).
Secondly, reading over this thread I'm pleasantly surprised--well, not all that surprised--to see just how similar the wish lists are. There isn't a lot of disagreement; sure, there is some, but there are some pretty strong generally held hopes for 5E. It is sort of like DNA - we share 60% of our DNA with bananas, 70% with slugs (which makes me wonder how much DNA slugs and bananas share, but that's majorly off-topic), 80% with mice,
My point being, there are some core similarities between what everyone gets out of the RPG experience; the "shared ethos" starts diverging the more detailed we get, and the greater number of folks, but I think there is a sweetspot where you please as many people as possible and still create the game that you (the designers) want to play, that is innovative, etc. Considering how finicky gamers are, I think it would be possible to start at the banana level (proverbially speaking) and create a game that pleases 60% of D&D players, if the core is simple enough and focuses on archetypal fantasy tropes.
That sweetspot can be extended, though, through the simple core/modular options approach. Create a simple core game that can easily be learned within the cozy confines of a lovely box set, and then expand that game with the Basic core at the heart of every product, but with easily exchangeable (modular) rules options for pretty much anything you want. This, I think, could please 70-80% of D&D players and bring us up somewhere into the slug-to-mouse range.
Is it possible to get to 90%? Probably not, both because of what you say--the unavoidable disgruntledness--but also because of basic human psychology, that most/many of us make decisions first and foremost through gut feeling and affective response, and then secondarily through logic and reason. That isn't a bad thing; I personally try to combine gut/intuition and logic/reason in my decision making, but I admit to frequently following the former over the latter, and I don't think it is "wrong."
So I think WotC needs to think about how their presentation and PR impacts people, how people respond to art, and what the "feel" of the community is. The Paizo community is much more tight-knit, harmonious, and "homey." Even though they've become a pretty large RPG company (my guess is the fourth biggest ever after TSR, WotC, and White Wolf?), they've managed to retain that "mom-and-pop" feel. Can WotC recapture that? I'm not sure. They need the right people, and they need to differentiate those folks that are good at game design and those that are good at PR and community building; the two aren't inherently mutually exclusive, but they are very different skill sets.