The 3e lineage is about rules mastery. You win it the week before the campaign starts, by planning your next dozen levels of cunningly broken prestige class interactions, optimizing every magic item slot, and stacking a zillion buffs. You're hungry for every level as that master plan slowly unfolds. Breaking the system is the fun, and a system that's been crushed under its own bloated weight provides endless opportunity.
I was about to take you to task on this, not least because I don't include any PrCs in my game, until I read:
..admittedly, I'm caricaturing the editions outrageously...
So, yep. Let's go with that. And I'm glad you can get something out of every edition. Your underlying point, that each game rewards a different style of play, is entirely reasonable. But how much does it address the concerns expressed in this thread?
I'll confess to being a little unsympathetic to the concerns of D&D fans with vast libraries spanning generations of the game who bemoan the relative lack of material aimed specifically at the latest edition. At the same time, though, I do wonder what people new to the hobby think when they go to a store, see a wall of PF stuff and only a shelf of D&D. Some might indeed be put off by the wall. Others might think, "Well, that's where the action is."
I don't play PF but that's only because I'm happier than ever with 3e (and yes, I'm also playing and enjoying 5e), so I have nothing but admiration for what Paizo has done with PF. I just want D&D to thrive, too. So, if D&D requires more support to ensure that, then by all means let's see more support.
For the moment, however, I think there's probably just the right amount of 5e out there and that WotC is pacing itself for the long game. I know that's just a gut feeling. I concede that there are some compelling arguments that the 5e support strategy may not ultimately be for the best. But even then, WotC has the resources required to give its strategy time; if in a year or two it thinks it may need to step up its product publishing schedule, it will still be able to do so.
Or maybe it is time for D&D to begin repositioning itself as a brand: not necessarily to be the biggest, having the broadest appeal, but to be considered the most prestigious, historically, aesthetically, mechanically and by association, for example (in which case, that latter criterion will need some work).