I let my dollars do the demanding. That's why I continue to subscribe to Dungeon and why I generally refuse to buy a new supplement or game that is not supported by adventures.
Yes, I have more gaming stuff now than I'll ever use. That's not the point. I've discovered that I like reading gaming books, even if I never play that game. For instance, I recently bought a GURPS WWII book on Finland. I don't play GURPS, but I am interested in that period of history. I probably won't keep the book now that I have read it. I would love to run it as a Savage Worlds (another recent acquisition) mini-campaign, but where's the time and interest, really? It has to get in a very long line of games I would like to run but for which I have no players interested. On the other hand, reading a new (or old but new-to-me) game book is great fun without all that extra work of running a game.
I've never used all the adventures in Dungeon, and I probably never will. I recently sold my AD&D stuff, including about 40 issues of Dungeon. It was hard to part with the collection, but I ran the best adventures (the ones that appealed most to me). My Shackled City campaign fizzled after the first 2 dungeon crawls. I may never get around to running the next 9 crawls in that adventure path, but I am interested in trying again with the new adventure path.
For me, a product's "newness" is a big selling point. I can't really explain it, but there it is. Games, including adventures, by and large have a short but brilliant shelf life for me. Luckily there is no shortage of recently-published material to keep me reading, DMing and playing!
Now, if I could just do something about my group size and the complexity of d20...