They get better up to the point where you have to reinstall Windows because everything's turned to sludge. Frankly I suspect the same thing's happening to my MacBook too. I can't prove it, but it sure feels slower than when I bought it.
If Chromebooks can solve this problem, whatever the root of the problem may be, then maybe they're onto something.
Okay, I mean some automatic updating software is bad. Adobe's is very annoying, and Windows Update frequently requires rebooting. But some are great -- like Chrome! On a Mac, probably the best thing about the app store is that it consolidates all my software updates (well, not all of them yet) into one place. So the UX is lacking in some places, but it's getting better, and I certainly don't agree with quote's implication that automatic updating doesn't exist on PCs or that software updates don't (in the majority of cases) keep adding value to a PC over time.
PCs undoubtedly get slower over time. OSx is way better in that respect but based on the data collected in our office Ubuntu kicks the ass of both OSx and Windows. Those using Ubuntu here have suffered no slow down in two years. I guess that this selling point will ring very true with consumers. I also imagine that google will continue to autoupdate (for free) the OS and, being Linux based, it is more likely to work just as well in 2 years (as our Ubuntu installs).
Chrome OS has a far more rapid development cycle vs. Windows and OSX (feature/performance releases come with weeks instead of months/years); and the updates themselves require next to zero thought. Worst case scenario: even if you never shut it off and ignore the update blip, you'll run out of battery eventually (at which point you're updated when you plug it back in).
The Chromebook has another advantage related to automatic software updates: by focusing on web apps, it ensures most apps are up-to-date (since web apps, due to the distribution medium, always use the latest version).
If Chromebooks can solve this problem, whatever the root of the problem may be, then maybe they're onto something.