Pedantry: BBX hasn't shipped yet outside the PlayBook, and I'd hardly call that popular. The phones are still running the original since-1999 BlackBerry OS.

And why not BSD? I'd mainly say mindshare, and portability to a degree. You don't have to release your source every time you port BSD to a shiny new platform. BSD code is out there (networking stacks, a handful of the base *nix utils in OSX), but the permissive license cuts both ways.