I don't appreciate being gouged at the airport, either. Sure, it's only $5... but there were six DLC civilizations, so now you're looking at $30, which is half the price of the game itself.
The problem here is that if people balk at paying more than $60 for a game, but eagerly slap down half again as much more money for tiny incremental DLC additions, then you're giving the developer a perverse incentive to put as little content as possible in the $60 box, and release as much content as they can as DLC, for which they can earn something like 20 times the profit. If you don't see this as a recipe for disaster, you're not thinking hard enough (or you haven't played enough EA games).
I think Firaxis learned their lesson with the early Civ V DLC's, and I think that's why they released G&K and BTS as more conventional expansions.