“We will never catch up. We will never fill all the capacity that Moore's law is heaping on us. The way we get more functionality these days is by doing more and more leveraging of existing infrastructure and existing applications. As systems are becoming longer lived, versioning is becoming more important.” [Anders Hejlsberg, Part IV of the Artima series of interviews]
Finally, someone who is very smart refutes those who demand that software be rewritten from the ground-up. Remember, don't do what Netscape did.