While I'm sure your comments are valid regarding some who are experiencing upgrade issues on the older iPads, I have to disagree that this is the norm. I know full well I'm running a 4-year-old piece of technology, and I don't expect it to be able to keep up forever. I can live with that. My rant is based on my belief that whomever decided to enable one to upgrade to iOS 8 on an iPad 2 should have taken into account the user experience following upgrade, regardless of whether the upgrade is technically possible. As it was, I mistakenly relied on Apple's assurance that an iPad 2 was a viable platform for iOS 8. It is my experience that while the new OS will run, it does so exceptionally poorly.
I would have been happier if Apple had simply excluded the iPad 2 from the upgrade, or had at lest provided a solution along the lines of "iPad 2 devices may or may not work with iOS 8, depending on your situation and the mix of apps you use. Here's how to upgrade try it out, and here's how to restore iOS 7 if you find your results are not adequate."
I agree with you regarding Microsoft doing similar upgrades -- it is not unusual with something as significant update to an OS to find that something does not work well. The difference, however, is that in the Microsoft world I could always revert, albeit painfully, if I did not like the upgrade. Apple has taken the ability to revert away, and that, in a nutshell, is why many of us now find ourselves carrying around devices that perform so poorly as to be useless in most situations.