I don't think I follow. In what sense is Android horribly insecure? More interestingly: in what sense is it horribly insecure that it wouldn't be if we lived in a world where Google didn't have the market agreements to, say, force security patches for pieces of the Android OS core that were broken?

Because we already lived in that world, and it was less secure than the one we live in now, to my memory. Security issue in one of the Android libraries that are now part of Play Services? Good luck; wait for your OEM to update your OS.