C'est très intéressant.
In contrast, the GPL has enforced a consortia-like arrangement on any major commercial companies that want to use it. Red Hat, Novell, IBM, and many others are all contributing as a result, and they feel safe in doing so because the others are legally required to do the same.
So while the BSDs have lost energy every time a company gets involved, the GPL'ed programs gain every time a company gets involved. And that explains it all.
Yes, companies could voluntarily cooperate without a license forcing them to. The *BSDs try to depend on this. But it today's cutthroat market, that's more like the "Prisoner's Dilemma". In the dilemma, it's better to cooperate; but since the other guy might choose to not cooperate, and exploit your naivete, you may choose to not cooperate. A way out of this dilemma is to create a situation where you must cooperate, and the GPL does that.
Again, I don't think license selection is all that simple when developing a free-libre/open source software (FLOSS) program. Obviously the Apache web server does well with its BSD-ish license. But packages like Linux, gcc, Samba, and so on all show that the GPL does work. And more interestingly, they show that a lot of competing companies can cooperate, when the license requires them to.