I'm still new here, but I'm going to offer my two cents anyway.

I've wanted to get into a project similar to this for a long time. I think that while the focus should remain on the maps themselves, there is always room to flesh things out. I don't believe that fully realized adventures are necessarily the way to go, as you are then limiting yourself to a specific rules system. I do think that detailed descriptions of important places and people, including their histories and motivations, would be an inspiring source for any motivated DM.

In short, the guild provides the fluff, and the DM supplies the crunch.

I really hope all that made sense.