Of course there are multiple rationales for choosing a platform, but support is certainly one of them. A while ago someone made a nice graph of how good Apple/Google are at maintaining OS support for their devices, it's pretty informative (although I'd like to see a new one). http://www.fidlee.com/android-support-vs-ios-support/ In this case the Nexus 4 is still officially supported by 5.0... but not being able to ca…
Most of the Android phones on the page you linked are not Google phones. Whether or not they get updated is up to the manufacturers and carriers, not Google. You'll note that the Nexus phones have more update support in general.
Whether providing major updates to a phone is a good thing is debatable. My wife hated getting the 5.0 update. She saw it as a major inconvience that changed how her phone worked for no good reason. She would prefer to have the phone work the same way for the entire time she owns it.
PS: 'Sup, fury?