To me, the perfect example is the MS office icons - in 7, MS dropped the text-labels off the taskbar entries. This would make sense if they had any kind of consistency, but MS office has had a complete makeover with every release, not even sporting a consistent color-scheme.
I wouldn't even object to paying for those kinds of upgrades, if I needed them, if I could take them without getting a bunch of unwanted tinkering with the UI and toolset.
I eventually gave up on Windows as my primary OS because of many small, incremental breakages like changes to the batch language (without really fixing any of its serious shortcomings), it becoming impossible to do a simple file search from Explorer, then it becoming impossible to change file associations without a 3rd-party tool. But hey, if you want an animated dog for no reason, that's no problem!
I still need Windows 7 for some things (3D software is still almost exclusively Windows-only) and I still find certain things about OS X a bit clunky, but overall I'm rather happy that I no longer have to care about what Microsoft might mess up in Windows 9.
CPU architecture is hardly all that matters to the core OS
Pretty much everything else should be handled with driver updates or at worst a service pack.
Driver updates work fine for adding support for a new model of graphics card, but when you introduce a whole new kind of device (e.g. WiFi, SSD) the implications reach into the OS itself. They managed WiFi in a service pack for XP, but it was both a pretty unprecedented level of change for a service pack, and always felt kind of tacked-on.
Anecdote: I'm a software engineer who develops using Windows. But at home I rarely turn on a computer. I do most everything from my iPad. Though to be fair I often do most of my digital errands from work on my PC.
* Most consumers never directly pay for a Windows, or any OS really. They get whatever the hardware vendor installs.
How long can these guys go on releasing new operating systems? And how long will people keep buying them?