A few questions:
1. Why is the sole determinant of third-party d20 publishers having "failed" whether they produce D&D adventure modules?
2. Why is the success or failure of d20 and/or the nurturing of the next generation of D&D DMs all being laid at the feet of the third-party d20 publishers? Isn't this primarily WotC's responsibility, seeing as they have the most vested interest in the continued health of the D&D fan community? That said, why is the fact that WotC released a whole series of adventure path modules, a couple of "mega-modules" (RttToEE, CotSQ), free adventures on their Web site every month, 3-4 adventures via
Dungeon every month written by many esteemed designers, and now are releasing a path of modules for Eberron, not to mention a new Basic Set... being totally ignored?
3. When was it determined that third-party publishers *weren't* releasing modules anymore? Sure, some publshers are dropping out, but there are still companies out there producing them, e.g., Necromancer Games, Goodman Games, others I'm probably forgetting, and a host of PDF publishers.
4. Why is "Well, I didn't know about that" a valid excuse for the claim of these publishers being "failures"? Why should we assume that the average geeky 15-year-old won't have the presence of mind to go to
http://www.google.com and do a search for "D&D adventures"?
5. Why should it be assumed that there is any direct link whatsoever between lots of third-party modules being available and the quality of a nascent DM's gamemsatering skills? What do the two of these have to do with each other?
Overall, I'm glad that publishers have chimed in to reveal some of the flaws in the logic of this thread's premise.
As for me, I never bought many modules as a kid, and I'm a freaking great GM.

I made up my own adventures and learned as I went. If anything, it's other GMs that have taught me the most about the GM craft, not published adventures.
If there was to be a resurgence of module publishing, it'd just be that much more product that I don't really have much use for. I already subscribe to
Dungeon. Between that and the modules I've bought (some Atlas, the WotC mega-modules, the adventure path, Eberron adventures) and the ones I've won at Gamedays, I already have more adventures than I could hope to run in a lifetime. Most of them just gather dust on my shelf.
If anything, I lean more towards d20 products that do interesting things with the system, e.g.,
The Psychic's Handbook,
Grim Tales, RPGObject's Blood series, TGM's d20M books, etc. And, actually, the d20 product I'm most in love with right now is Goodman Games'
Power Gamer's 3.5 Warrior Strategy Guide. Imagine, a book that helps me make better use of *product I already own*. Booyah!