I think a lot of devs come to prefer BSD simply because of the importable library situation, and their dev background is just writing more and more internal libraries for their company's product.

The GPL works well with the unix philosophy of having many small programs that do small things. There's no problem with taking some of those programs and using them in your proprietary project since you're just running them independently, and come distribution time you just ask (or release an open script that does it as part of your program's install process) the user to install system dependencies if bundling them yourself would constitute a derivative work. The problems with the GPL come when you try to use or bundle the programs a little too closely. It becomes important for libraries/modules to not be GPL so that you can still import foo and not be required to release your whole program under foo's license. Hence GCC has the Runtime Library Exception, and most third party modules for languages have similar exceptions (typically by being under a BSD-style license).

In the background of many corporate workers, the only approved way to write code or use third party code is as an importable library to use in their company's product (which may be a multi-million line behemoth). Writing little self-contained programs isn't very common for them, nor is using other programs as spawned subprocesses. (The exception where that may be more common is the case of web applications where the used programs aren't AGPL'd...) And so since importing any GPL library introduces a semi-uncertain (uncertain in whether a court would convict) hazard about whether the company's whole multi-million line behemoth is now a 'derivative work' for including a mere multi-thousand line bit of FOSS, devs will avoid GPL libraries entirely. The motivation for BSD-like licenses for using (or writing, then using) bits of code then is simply a matter of using them at all due to the library issue, and I agree that having at least the base code available later is icing on the cake that makes the decision even more easy. But I think if a dev's corporate background is in a culture that follows unix philosophy more with lots of different programs, they won't necessarily reach for BSD-style licenses on instinct even for things beyond libraries.

In one sense proponents of the GPL are opposed to the idea of abolishing IP since copyright law gives the license its teeth, while BSD guys would probably be fine if they were forced to make everything public domain (but still might ask for credit as a kindness even if not legally required to do so). But there's a bit in Stallman's free software song that I think shows the GPL guys could have the same perspective someday: "When we have enough free software/At our call, hackers, at our call,/We'll kick out those dirty licenses/Ever more, hackers, ever more." That was written in in 1991, there wasn't much free software then. I think at this point in 2015 we have so much source available, that if we're not there, we're at least very close to the point where we don't really need the viral nature of the GPL to force companies to release the source. Many companies produce entirely new works that are under a BSD license, there's nothing that compels them to do that but a dev culture where Open (if not necessarily Free) has real benefits even to the money guys and has won. GPL code now hinders many pragmatic devs who just want to include a tiny useful bit of some Program (i.e. one of its internal libraries) rather than work out how to use that useful bit indirectly by just running the program, and instead of having code reuse we're constantly reimplementing things. I can't just reach into git's source code and pluck a few useful functions I like for my own project like I can with the Python standard library. (I'm glad to know that if I ever need an approximate fraction function in JavaScript for a proprietary work, I can use the one I made based off of https://hg.python.org/cpython/file/822c7c0d27d1/Lib/fraction...)