I see what you mean. No don't get me wrong. Apple is working on this problem. Slowly, but surely. And it's no easy feat.
Retail is a cutthroat world and high numbers control the shelf space.
To that end Apple now has a games software section right on their own web site. You can grab a copy of all the latest and greatest Mac games right at the Apple Store . Well that's pretty cool. But Apple can do some more simple things to get customers in the know about where all the great Mac games are available. For instance, they could include some pre-configured toolbar bookmarks on all preinstalled web browsers like a link to the Mac Gamer's Ledge and Inside Mac Games web sites.