And this thread pretty much sums up why they should ignore current gamers. It's not age, it's obsitnance. All the passive-aggressive edition war garbage so thinly veiled in this thread alone makes one wonder why the design crew should care one lick what this "community" wants. In a perfect world, they need to make a good game to appeal to new players while finding a way to make the current crew just STFU because they can only hurt their goal to grow the game.
Of course the internet makes things much tougher because motivated minorities spamming review sites all too much of a reality.
Don't forget, however, that many of the "grognardish/obstinate" crowd will still *buy* 5E, whether or not they plan on ever playing. That's half the battle for WotC, at least out of the gate. The other, of course, is making a game that is sustainable and attractive to a wide variety of demographics.
So I think the "answer"--if there is one--is not to focus on one demographic at the expense of another, but to find a simple core ruleset and default style that can form the basis for a wide variety of directions. This was the original design intention, afaict.
(Actually, as an aside, I empathize with the gist of what you're saying in that I feel WotC has really tried to approach the whole (or)deal of a new edition in the spirit of unity - finding what we all agree on, the "spirit of D&D," and making that the basis of design. Even then, some people found their attempts offensive, as if Mearls & Co were telling everyone what D&D Should Be To Everyone. As the saying goes, you can't please everyone - especially we gamers, who tend to be a rather ornery and finicky bunch).
So if you want to play relatively traditional, simple D&D ala OD&D and BECMI, but with a more streamlined core, then the basic game is for you. If you want a more tactical game that focuses on the battle mat, then the "Advanced Combat" module is for you; if you want simulative detail and endless customizations, then the "Advanced Character Design" module is for you. Or you can pick and choose from these major modules, and any number of other thematic modules they come up with.
The problem with both 3E and 4E is that both editions painted themselves into an overly specific thematic corner and couldn't get out. 5E will, supposedly (and hopefully), retain a simple core that could form the base for any number of play styles via modules, and all retain some degree of compatibility.
Heck, I even have a few silly "deal breakers". I want use of the full, standard set of polyhedral dice (I'd even like it if there was a use for percentiles soemwhere, if possible), character sheets and the majority of focus pre-Industrial revolution and gunpowder. I have nothing against "Steampunk", I just want it to be ancillary. I also want the game to be designed around actual teamwork.
As a side note, I agree on all accounts, especially the dice. One of my favorite things about D&D and one of the reasons I end up coming back to it over game engines that I find more aesthetically appealing (e.g. Ars Magica, Talislanta, Fate, etc) is the polyhedral dice. I love 'em.
Gunpowder and such could easily be a "theme module."