Android is one thing, but desktop Linux is another. Many people have heard of android or perhaps Linux on embedded devices or servers, but not Linux on desktops PCs. "I thought Linux was for servers."
As to providing a open platform, due to the laws of most countries were we sell our products, certain parts have to be closed source to protect our investments and our ability to sell into major markets. If you don't like the laws, call your congressman.
Also, Linux doesn't encourage the sharing of source between OSes. The maintainers want the code to match the kernel coding style and will reject code that doesn't match. There are tons of open source drivers out there that use an OS abstraction layer to share the code between OSes, but they are never allowed upstream in Linux. It's not likely that our closed driver would be allowed upstream if we decided to open source without out a major rewrite. So I guess it would be a good investment to rewrite thousands of man years of source code to get it into the Linux kernel and then write a proper infrastructure to support all the advanced features available for 1-2 precent of the desktop market.