That's an excellent point. I run across people from time to time who are really interested in the idea of RPGs. The woman at Staples who printed and bound the most recent issue of my zine was asking a lot of questions. She was intrigued by the imagination and stories that could be told. If my gaming group wasn't full, I'd invite her to game. Maybe next campaign.
I think that there are people out there willing to give the dice a go, it's just a matter of making a good sales pitch and catching them before they start playing WoW.