I've discussed and alluded to the idea in several past posts. I consider my self a "homebrew" GM/DM, meaning, I write most all of the adventures in my games. I rarely, if ever, use "pre-gen" adventures mostly because I don't "feel" them and thus do not run them as comfortably as I do the adventures I put together.
I'm not alone in the notion of sharing for free the things I create with the public. It's happened in RPG world for decades by those who contribute to magazines, online communities and elsewhere.
I like to pick up ideas as I find them from others as much as I like to share my own creations. Heck, I get ideas just from reading a discussion thread in a forum that inspires me to create something else.
I think it's important though for people to willingly create and share things they come up with, especially in hobby and gaming communities. With games like AD&D 1E for example, there isn't exactly an abundance of new stuff being made available commercially, even if I could afford to buy it and was interested in using pre-gen stuff.
This is why I like the idea of OSRIC so much and the Open Gaming License. Yes, I have the original AD&D 1E books but being such a full time home brewer, OSRIC and the OGL suits me just a bit better because I don't have to worry about some greedy SOB trying to make claims on something I share because they want to make a buck off someone else's work.
I particularly think 1E and OSRIC fit the bill perfectly because they are made for the homebrew GM to create their own stuff. pre-gen commercial stuff is available too, but the books are written for the GM who creating their own stuff.
From what I hear about later editions it seems that things changed to be more of a players game relying more on commercial pre-gen books and stuff leaving less "open" for the homebrew GM. Not to say that it couldn't or doesn't happen, but that it seems to come up much less frequently that people are homebrewing in later editions as much as in 1E/OSRIC.