Re: @ Jamie Jones
"I was sweeping the "GPL - bah!" side under "maybe idealist", though calling out separately "maybe pragmatic" would have been clearer."
Oh, I see now. Sorry for being (slightly) sarcastic in my reply!
From the wiki link:
"....that the engineers who had written the Solaris kernel requested that the license of OpenSolaris be GPL-incompatible. "Mozilla was selected partially because it is GPL incompatible. That was part of the design when they released OpenSolaris...."
Assuming that is correct, that may again have been because they didn't like the inherent rules of the GPL rather than "It's GPL,ARRRGH"
But I see your point. There are fanbois on both sides :)