Ah but thats not it at all, Lodsys didn't invent something either, they purchased the patent from someone else, who purchased it from the inventor.
Well, they purchased it from a guy who was the first to patent an obvious idea with little or no intellectual value.
Patent trolls exploit the fact that the patent office does not have the resources to properly research a patent application before granting the patent. As such, patents with little or no value are often granted. Patent trolls use these patents to wait until a rich company uses something even similar to the idea expressed in the patent and they sue, hoping for licensing, a settlement, or a court victory in East Texas.
That's the problem here - the patent office is a joke, and these scumbag trolls are taking advantage of it.