Linux didn't win because it was GPL'd, it won because it was the only real alternative back in '92. The BSDs were all caught up in the moronic SCO lawsuits of the time, otherwise we'd all be using FreeBSD or some other 386BSD variant today instead of Linux. The GPL was a nice bonus but it isn't the real secret sauce that has powered Linux's growth, it was mostly good timing.
That doesn't mean that I'd rather see some form of copyleft in place (like the MPLv2) or at least a licence with some kind of patent protection baked in (like the Apache 2.0), the X11/MIT licences are extremely weak against patent trolls
The short window of opportunity that had opened up around 1992 certainly was a precondition for Linux success.
That we have Linux as we have it today is the result of
- being under GPL
- having a large enough and diverse enough group of contributors to make re-licensing practically impossible
- no CLA, no Copyright assignment