Now here's an idea for how a big company like Wizards of the Coast could make money off of people playing the game. In short: set up a big ol' database, and let users fill the database full of stuff. Characters, adventures, maps, encounters, that kind of thing. Other people rate, rinse, repeat.
I'm not sure it can be done. Not without the rating system turning into a morass of greifing, anyway. (Anyone played City of Heroes lately?) But if it can be done . . .
Heck, if access to the database was based on a subscription, then you could send micropayments back to people whenever someone downloaded their stuff. Even if all it could amount to was getting that subscription for free, it'd be a pretty good incentive for people to polish up their home adventures and send them in.
But pie-in-the-sky figuring like this is beside the point. What's important about that post is that it's another person who's come to the conclusion that the best way to build an industry off of supporting play is to publish adventures.
Most of the current industry out there has pretty obviously decided that publishing adventures isn't worth the time or the money. And they're probably right -- in the short term. In the long term? Adventures do a lot of things to grow the player base that can't really be done any other way.