I haven't been on this forum in ages, but thought I'd toss my hat in the ring.
I've played Basic, 1E, 2E, 3E, 3.5, 4E, C&C, and a number of other RPGs over the years. What I have found in recent years is that complicated rulesets get in the way of what are, to me, the most important aspects of the game: roleplaying and storytelling. I'm not saying they will get in the way for everyone, but they certainly have for me.
I like combat and exploration as much as the next guy, but I also find both of those things way less fun with what are, for me, overly complicated rules. I find both 3.5 and 4E combats incredibly tedious, for example. These days, if I want to play D&D I run Basic. The combats we had using Red Box were way more fast-paced, exciting, and tactically interesting than our 4E combats. But I'm not really an OSR guy, either--the old editions have a lot of design features that I consider, frankly, inelegant, and I always come up against them when I try to play the old editions. I know why they're there: because rules were tacked on piecemeal as the original players made things up as they went along.
That's fine, but I like simplicity
and elegance, and I especially like rulesets that not only don't obstruct, but actually
facilitate the kind of play I like, which is heavy on roleplaying and storytelling
in addition to combat and exploration. In fact, what's really fun for me these days is the shared experience of co-creating a story (preferably one set in an awesome fantasy world).
My friends and I played a 4E campaign a while ago and I found that the preoccupation with powers left players thinking more about developing their
builds than developing
characters. Eventually it got to the point where I flat out had to tell a couple of the other guys, "I don't want to hear about your powers. I don't care." Interestingly, this problem didn't occur at all when we later (i.e. after that campaign collapsed) played In a Wicked Age. FWIW, after that first night of In a Wicked Age (which I GMed) everyone said it was the most fun night of gaming they'd ever had, and a couple of them were hardcore nerd/computer game dev/4E fans. Not the kind of people you'd expect to dig an artsy/indie/pretentious storytelling game.
Computer games are more than capable of delivering a satisfying exploration/combat experience. What tabletop RPGs can do, that nothing else can, is provide that shared, imaginative storytelling experience. With rules to facilitate that process, of course.
I've also found that now, at the ripe old age of 26, with a kid and in grad school, etc, I simply don't have the patience for complicated rules. Not as a player and even less as a DM. And I sure as hell don't have the patience to explain them to new players, who often these days aren't gamers or even nerds, necessarily (until they sit down at my table

)
I understand the argument that WotC needs the complexity because they need to keep publishing supplements in order to survive. IMO, that is because their business model is flawed and not good for the game. 21st century D&D is bloated out of all proportion, especially 4th edition.
At the same time, people love the D&D brand, and it is so retro that it is almost cool. I used to be self-conscious about people knowing I played D&D, but now I make D&D jokes even in mainstream and indie/hipster type circles and someone always laughs. I walked into the hipster coffee shop I always go to yesterday and the barista was wearing a Red Box t-shirt from ThinkGeek.com.
If I owned the game, I'd create a one-box or one-book new edition, something of a bastard lovechild of Basic/1E, 3.0, and Narrativist goodness (think 3E without skills or feats, just ability checks vs DC, action points, and some mechanics designed to facilitate improvisation and player influence on story), slap a retro cover on it, get it in mainstream outlets like Barnes & Noble and market the crap out of it in all the places WotC never would. I wouldn't make more than half a dozen supplements. Ever. I'd just focus on selling as many copies of the core game as possible.
You may say that wouldn't be viable, but then again in my fantasy I don't have to worry about paying all those employees I wouldn't need (no splatbooks for them to write) or about making money for Hasbro.
Hmm, who else can I offend...
Anyway, people, remember this is all just my biased opinion and subjective fantasy etc. YMMV.