Epic Games' Cliff Bleszinski, famous for his work on the Unreal Tournament and Gears of War series, has gone on record stating that many Japanese developers are leaving an opportunity on the table by skipping out on co-op and multiplayer modes in their games.  While Bleszinski said he doesn't believe every game has to have a tacked on multiplayer experience, there's definitely room for it in titles because of the replayability it adds.

It’s something we’ve thought about, and finally someone had the opportunity to ask - but where is the co-op campaign for the testosterone-fest Bulletstorm? We know, we know. There is always Anarchy mode, complete with four-player co-op - but what about the story? According to the interview with Epic game’s Cliff "Cliffy B" Bleszinski (avid patrons of Bulletstorm), co-op unfortunately broke the game.