The source code for the new changes must be made available for others to see and learn from. The FSF position is that software is more akin to speech than a physical product to be sold. That's a noble concept for the nineteenth century. I'm sure Richard is correct, but it brings up an interesting dilemma. If the big kahuna of the FSF wants free software, he shouldn't demand the payment of fame for its use.
Some folks are just plain anticapitalist.
I'm not saying that Stallman is anticapitalist, I'm saying the whole free software movement is. But understand my distinction. Giving away software is a great marketing tool. It's hard to compete if your competition is free. That's something that a number of companies have discovered.