To demonstrate to them that homebrew beers can be every bit as good as commercial beers. Basically, just to get them over that first hump of considering that maybe - just maybe - homebrew beer isn't the scary, Frankenstein mess people seem to think it is.
I'm absolutely baffled that people seem to have this irrational, instinctive aversion to homebrew beer. I say, "Hey, can I get you a beer?" They say, "Sure, what kind do you have?" "I've got a nice medium-bodied pale ale and a stout." They ask, "OK, but what kind is it? Stella? Heineken?" "No, they're homebrews." Then they back away. "Oh, OK then, don't worry about it, I'm fine with water."
Everybody knows they can make a better burger than McDonald's. Everybody knows they can make a better coffee than Dunkin Donuts. But for some reason, people seem to think that brewing beer is the exclusive domain of the large commercial breweries, and anything you make yourself will be a disgusting concoction bearing absolutely no resemblance to "beer." I just figured having a nice, light lager to offer them might help dispell that prejudice and introduce them into the fascinating, complex world of craft brewing. Sort of a "gateway homebrew."