One thing I can imagine is even something like unconscious “self censorship”, choosing more permissive license to attract more people and even corporations which will hire developers…

This is the result of years of anti-copyleft propaganda which started to pay off. Now, all that corps need to do is wait for new projects and libraries to pop up and subtly (more than often openly) allocate resources to whichever project they need, or simply EEE. A much easier exercise than it was during the early years of copyleft where we could literally have a free alternate operating system to Microsoft, Apple and IBM while they were openly fighting it. Read on the Education and Government Incentives program for a reminder of what corporations are capable of.

I highly doubt these are sponsored by any big corp, just hobbyists/students that think it is interesting project to undertake that don’t care as much about the GPL as much as they care about doing something interesting to them.

I wanted to test this theory, quickly looking at the commit history you can see that although the project might have started as a hobby/student weekend project, it is currently maintained by someone with an official affiliation of director at Mozilla corp.

PS: I am not pointing the finger to any entity here, I picked this project as an example to have a discussion on this topic.