It's called "Update anxiety". This AC article explains it all quite well IMO (excerpt below, bolded part by me!

Highly recommend reading the entire article though! Very good info on the Android update process.):
Why you'll never have the latest version of Android | Android Central
Excerpt:
"As updates become more common, and consumers become more tech-savvy, there’s an increasing awareness that devices can be updated, and an expectation that they
should be updated. With that comes a sort of “update anxiety.” If you’ve dropped by any smartphone message board, such as our own forums or XDA’s, you’ll know what we mean by this. Threads abound asking when ICS, or Jelly Bean, will be available for certain devices. In the event of delayed or even canceled updates, Internet denizens swear they’ll never buy another phone from that manufacturer or carrier again. It’s an entirely negative ownership experience.
While this isn’t representative of the entire user base -- not by far -- it’s an example of how many power users experience Android smartphones. They’re always behind the curve,
always waiting on an update, never fully enjoying the product that they’ve bought as they’ve bought it. Part of that is the fault of the tech press -- we’re always focused on what’s new, and that means talking about software that hasn’t yet reached most folks."
Edit: adding an excerpt about the "Solution":
"The only true solution to the Android update problem is a change in mindset, or if that doesn’t work, a change of handset. Android will never be able to offer across-the-board updates like Apple does -- it’s technically impossible for the wide variety of reasons we’ve already covered.
Android phone owners, community members and fans need to appreciate that updates are hard to develop, and take time and money to put out, and when carriers get involved, they can be subject to long, tedious delays. That’s not the case with iOS and Windows Phone, but they’re very different operating systems. Painful as it may be to admit, waiting for updates will be part of the Android experience for many years to come.
But if Android is the problem, then perhaps Android can also be the solution, at least for technically adventurous users. Android’s openness enables it to run on multiple hardware platforms, but Google’s OS is also eminently hacker-friendly. Many leading devices have a vibrant custom ROM scene, where custom-built firmwares are available, often based on later versions of Android than are officially available for those phones. That means if you really, really care about running the latest version of the OS, you can crack open your bootloader and do so, at the cost of stability (and perhaps your warranty)."