"Because like Chrom(e/ium), Android is designed to be a large data sink for Google to feed The Machine."

Also maintaining the monopoly over the app market and getting a good cut out of every transaction within. A non google controlled device in the mass market can introduce new markets independent of google (and not paying them).

They would not like that.

Apple did the same thing. In the early days of OSX much of Darwin was open-sourced. Now, not so much.