Didn't Valve originally say that they would keep on working on the original l4d making new content and shit as well as for l4d 2?
By doing all the original campains for the "new" l4d 2, then the original really was just a beta. There has been pretty much no new content to the original at all. It annoys me a bit.. but just a bit. I'm not saying that I regret buying it.