Some folks think beer is like a can of soup—you can leave it on the shelf until you're ready to drink it.
But the vast majority of beer is more like a loaf of bread—it tastes best fresh from the oven, but eventually gets stale and moldy. Local beer is on the up-and-up because it's got that “fresh-from-the-oven” taste, and drinkers love that quality. When a casual drinker has a supreme drinking experience trying a local beer, they'll immediately taste the difference—and never go back to their old macro standby.
We're not saying that you should immediately replace every brew on your tap list with a local one, but local beers are worth experimenting with because they have the opportunity to be fresher and thus better. Here's the science behind why it's worth it to serve local beers.