And more importantly, history has shown that permissive licenses just don't work in some situations. The BSD code was open and free to use under a permissive license. What developed around that same time was not an open and fair system where every worked toward the common good but in fact a closed competitive system where everyone kept their improvements to themselves in the name of competition. Such a system would still exist (and the reinventing of the wheel over and over again) had Linux not been licensed with the GPL. The restrictions in the GPL force cooperation on the community with entities that if given the opportunity would close up and refuse contributions.
IBM even made a public statement that were Linux not GPL they wouldn't contribute for fear competitors would use their work and improve and not give back.
So you might argue permissive is better, but I'll argue the GPL is better because it forces everyone to equal footing. A real study of the issue would be needed, but I'd be willing to bet that in almost all circumstances (yes there are exceptions that IMO are more about timing than license) a GPL project will move along better than a permissively licensed project.