Way-Back-When™ when I used to eat ASL for breakfast (if you don't know what Advanced Squad Leader
is, you'll not be able to appreciate that statement), although the community playing ASL was fairly small--kind of like the AGEOD community--my greater worry was not finding enough time to play all the scenarios I wanted to play, and not the other way around.
The community created many of the dozens--nee hundreds--of scenarios available, very often publishing them in fan-zines--player-created magazines--accompanied by articles on history and pertinent rules. A few of the fan-zines eventually went professional, and in fact, Multiman Publishing, which now owns not only ASL but also bought nearly all of the remnants of Avalon Hill's intellectual property, but a large number of other series and stand-alone games as well, started out publishing the fan-zine Backblast, which was at the time one of the most respected.
So why does ASL enjoy such great community support and such a proliferation of playing aids and material?... I believe, because It was fairly easy to do. One aspect which AGEOD will never have the ability to enjoy is the simple fact that ASL deals with squad tactics. Any major or minor battle from 1936 to nearly into the '50's could provide a source for an handfull to dozens of unique scenarios, from short 5 turn chess-puzzle like scenarios, to mini-campaigns. It is fairly easy to define the boards being used and 2 OOB's, possibly a couple special rules to put a scenario together.
So, why does the same thing not happen in the AGEOD community? IMHO this first issue with smaller scenarios is that they often don't feel right. AGEOD games are strategy games, which means in a grand campaign spanning an entire war, a campaign the player creates within a grand campaign scenario play-through ALWAYS has to consider the position it will put the player's forces in, once the goal of the campaign has been achieved--the Win-the-Battle-but-Lose-the-War™ conundrum--which to my knowledge could only be reflected in a small scenario in AGEOD games with great difficulty.
The other major issue is that it is an huge amount of work to create even the smallest of scenarios. The game engine simply does not lend itself to creating a scenario on-the-fly--aside from the fact, that there is a fairly large learning curve to even learn how to create a scenario. You cannot simply take the set of defined units in the game and Drag-n-Drop™ them onto the map and define this as the starting setup of your scenario.
Also, thinking ahead to what if it were much easier to create a scenario, is that scenarios in general are very inflexible. You can only create a fixed setup of units, over which the player has zero influence. The player is always confronted with a situation, in which he might often say to himself, I would never have my forces organized like this, or positioned here in this fashion. With a board game you can easily simply state, these forces setup with x regions of region A, or within this area, or enter the board between this hex and that one on turn Y. And I haven't even mentioned victory conditions...
Creating a good scenario is simply a huge amount of work. The things which might make creating scenarios much simpler and far more accessible to every player I've mentioned above. With the right tools, we would likely see a large number of community created scenarios, and not constantly wait for the AGEOD devs to put things together for us, for which they really have very little time, nor motivation, IMHO.