The only reason there is one Linux kernel everyone uses is because of the license. If it wasn't GPL2 there would be "Microsoft Linux", "Google Linux", "Oracle Linux" all with different features and potential incompatibilities. At least with the GPL2 license those flavors have to contribute changes back upstream so everyone gets the benefits.
>> It seems to me that your examples rather show the futility of trying to use a license to force good behaviour rather than a reason to change licenses.
If not for the license there would be NO good behavior. Notice that nVidia is relatively Linux friendly with some exceptions and RedHat seems to be under pressure to make more money but is otherwise very Linux friendly. Without the license, all sorts of others would be blatantly ripping it off.
I contend the difference in popularity and success between the BSDs and Linux is most likely due to the GPL license.