Earlier quoted context omitted.
It kind of is Google's fault. Most people associate any version of Android with Google. Manufactures that don't update their phones causes harm to both the manufacture's image and Google image. Personally, I place all the blame on Google for not making the upgrades possible from their side. It should be easy to upgrade the core operating system as easy as updating Windows, OSX, and Linux.
I dunno. Enthusiasts may track the versions coming out of Google HQ. But for most updating is a hassle rather than something they look forward to. This because it means downtime for their device, and if the update fails it may leave them with a bricked device (chance is small, but it is still in the back of their mind). For most people a computer, a phone, or a tablet is an appliance.
We are getting closer to the point where being secure and up to date is almost painless. That should be our goal in the tech industry.