And to be honest, there aren't a lot of lightbulbs waiting to be patented. No one is going to find a seventh simple machine. Invention isn't so much a process of aha! as it is of hmm. It's about looking into the current state of technology and finding a good place to continue. This is particularly true when it comes to software development, and it's interesting that developers themselves have been vocal opponents to the idea of software patents. But holders of patents are, by and large, not inventors but corporations, and for them the main attraction of patents is to build up an arsenal of potential lawsuits or to protect themselves from said lawsuits.
Back in the 1970's there was a Parker Brothers game call The Inventors in which players would purchase zany old-timey inventions, patent them, and then seek royalties. Amusingly, the inventions themselves were all of questionable value and completely interchangeable from a gameplay stance. One concern was that until "patented" the inventions could be stolen by other players. So the lesson was not that patents help to bring useful ideas to the market so much as they are chips in a legal game. While I don't think satire was the goal of the game designers, they got this all pretty much on the nose.