Allow me to posit that this is the most important factor of not only 4E, but of D&D as a whole, and therefore is a positive rather than negative factor.
I, personally, wouldn't call it a positive or a negative factor, inherently. There are some things it will be good for, and some things it will be bad for, but that's true of any choice.
The central/spine factor of Dungeons and Dragons has always been, since the 1st printing, that it is the Market Leader and First-Brush Role Playing Game.
Central factor for what? I mean, it has been, sure, but it also has been that without a real tenacious marketing meddling like 4e is getting.
If the initial success of 4E continues, it will transfer the commonality of D&D to the current system. If it can be reasonably proven that the system has been a success in it becoming the base-line comparison of table-top role-playing, than the system is a good one. This precludes arguments over the inclusion of Half-Orc or Sorcerers.
Well, all it really would prove is that adding more brand blitz to the equasion doesn't mess up something that is already leading, by letting it continue to lead.
What WotC hopes from this, I believe, is that "D&D" can be recognized outside of the context of PnP RPG's, and to increase the awareness of it outside of gamer circles (to grow the brand). If someone says "Tiefling Warlock" you should know that's D&D, just like when someone says "Night Elf Hunter" you know that it's WoW, and when someone says "Hogwarts" you know that it's Harry Potter, and when someone says "Gimli and Legolas" you know that it's Lord of the Rings.
4e, it seems, is
very focused on this goal. It's not about being a "good system" per se (though I'm sure they see that as something of a prerequisite), it's about being part of the zeitgeist.
For one reason or another, "Half-Orc Barbarian" and "Gnome Bard" were not considered as key to that strategy. It would be wrong to say that they don't care at all, they just don't care
quite as much.
The 4E "marketing" you note is a desired aspect of the system, arranged to create the most successful possible product.
I agree, but jumping the shark on
Happy Days was trying to do the same thing. "New Coke" was trying to do the same thing.
Those are famous failures, but there are plenty of successes, too, they just tend to be less famous because if it works, you shouldn't realize it unless you're a canny observer.
And making the most successful possible product is not the same thing, by any stretch, as making the highest quality possible product, or the most interesting possble product. McDonald's is wildly successful, after all.
Again, despite these comparisons, this isn't a positive or a negative thing by itself. It just forces some choices, which are good for some people (perhaps even the majority!), but it's not gonna work for some others.