You said it yourself, Susan: "it makes far more sense to spend it on full-page spreads in EGM or on banners on a gaming site like this one, because that's where people already predisposed to buy games are likely to see them"
The bottom line is that the marketroids are going to feel that the 'Return On Investment' for targeted advertising is going to be much greater in the millieu that gamers haunt than by doing a wide-spread, far-flung campaign.
And to be honest? The data to this point supports thier hypothesis. Only the big-time games, like Halo, like WoW, are broad-spectrum targeted. ("I'M A NIGHT-ELF MOHAWK...!)
I really think this is a chicken+egg scenario that will play out to a specific result: the marketroids for games are going to stay away from the mainstream until they get survey data that indicates that most homes have a console of some sort in them: then we'll see gaming ads during the Super Bowl (the most expensive advertising time on a per-second basis).
Personally, I wish the game companies would ardently (ha ha, see wut I did ther?) pursue developing markets, but I just don't think that a conservative business strategy supports that possibility... particularly during a recession.