Remember though that "Android is Linux", only applies when you are not discussing malware.
If you are discussing malware, "Android isn't Linux".
Android is, in effect, a Java framework with some device drivers. So that JVM could run on anything... Google just chooses a Linux kernel because its free.
That is most probably one reason. The other is that the Linux kernel is very good. I have never had a BSOD in Linux.Google just chooses a Linux kernel because its free.
In Linux, they're called Kernel Panic's, and they do happen for the same reasons they happen in Windows, bad hardware, or bugs in drivers primarily. The difference is that Linux doesn't typically have third party drivers (there are some, but not many) so kernel developers are writing the drivers, rather than hardware vendors who are much less vigilant. However, that also means you don't have the driver support that you do in Windows (although it inversely means Linux tends to support ancient drivers for old hardware more).
Here's an example:
Never had "Kernel Panic" on bootup !!! - It can happen - especially if you are testing "Development" or latest kernels -- which is the equivalent say to testing the latest Windows 10 release. I agree normally that stable released versions of Linux distros rarely if ever fail.
However Linux on the whole has a more "Computer Savvy" user set and sometimes if you want to add hardware you have to write your own drivers or wait until someone has developed one. Linux makes perfect sense for large commercial servers (organisations such as Red Hat etc) but Windows is still king of the desktop.
For Mobile devices (other than phones) it's still all to play for. Linux kernels can be incredibly small so perfect for say small tablet type devices. OS overhead is far better than Windows so battery consumption can be much less too.
I doubt that Google chose a Linux based solution just because it's free. A company like Google isn't short of a few dollars. It wrote Android because IT could control what went into it and wasn't dependent on having to use proprietary closed source code from Ms / Apple etc which could change at unpredictable intervals causing the inevitable chaos with users when some phones would fail and would cost hugely more to fix than by controlling the whole thing themselves. They could also port the OS to other Google devices. Google Cars are probably the next big Linux development.
To put this another way. You can't just take Windows apps and run them on Linux without emulation or Wine. You can't take Linux apps and run them on Windows without the same. Android, on the other hand, can run on any kernel so you can take those Android apps, and port the basic JVM to a different kernel and those android apps run just fine.
Your last point is.. well, not really a point. Phones don't just miraculously update their kernels by themselves. I'm not suggesting that they run a full Windows and then run Android in a window. They could have shipped Android with any kernel they wanted to, and it would only update when Google themselves updated it.
So back to the point... Android is not Linux. Android is a Java based application framework that runs Java applications that use that framework. Nearly all commercial versions use a Linux kernel to run that Java VM, but that's not what makes it Android.
Here is somebody that likes both Linux and Windows 7. I say I use them equally. Just because people use Linux, doesn't mean they hate windows and vice verse.
Here is some internet statistics that agree with lee as well as whs
Usage share of operating systems - Wikipedia, the free encyclopedia
I do see the desktop market share changing if Windows 10 doesn't go to well and when windows 7 extended support ends. I also see the market share changing because of Ubuntu and derivatives. I am totally against subscription based operating systems. I don't know if OEMs would support a subscription based operating system, let alone retailers and mom & pop computer shops.
Lee, your comment was really uncalled for. I am a Windows pro and do Linux only as an amateur. But it is necessary to point out the importance of Linux in the IT world. And as you know, the desktop is going to decline and the mobile devices are going to increase - and with those the servers. And that will be more opportunity for Linux based systems.