Do embedded device vendors deserve our trust to make good decisions ? They don't display outright malice, but they are institutionally set up to abandon software after a few years, as software maintenance is only ever a cost center.
Unfortunately management doesn't care about this aspect of their business, and has to be dragged kicking and screaming to a world of user-upgradeable software.
Are you actually comparing Darwin vs Linux, or OSX vs GNU?
Proprietary software has many advantages over Free - heavier corporate investment creates more consistent and polished results. But that doesn't imply that it's better for all purposes, or that a new project is better off choosing a license that makes easy to incorporate into proprietary products.
Darwin is an OS (the kernel is called XNU), so I was comparing it to Linux-based OS's. Darwin is the basis of both OS X and iOS. I agree that whether or not proprietary or copyleft is better or worse for a given situation is hard to say. A BSD license simply leaves the door open.
Unfortunately management doesn't care about this aspect of their business, and has to be dragged kicking and screaming to a world of user-upgradeable software.