The end result is that CLISP is one of the better CL implementations, and seems to have a pretty decent following. I don't know if it was like that before it was GPL'd or not, though.
This is not to say that we should judge GPL by RMS' personality - GPL, just like companies people create, will stand on its own; all I am saying is that GPL is strongly influenced by the personality of its creator.
Personally I find the GPL distasteful; because it locks you in. Frustrating (and I cant help feeling causes substantial code duplication for some projects that dont want to use GPL code)
(disclaimer; Im not personally a fan of Stallman, so I might be a bit biased over it)
That's probably true of any license based on philosophy. People who don't agree may be inclined to reinvent the wheel just to put it under a license they do believe in.
Were there any licenses prior to the GPL that didn't do that? Surely you couldn't just take a piece of IBM or AT&T's code and put it into your programs with no strings attached. That era was before my time, so please educate me if I'm mistaken.