1. You are copying a bunch of files from one place to another. There's one file with the same name at the destination. The system asks you if you want to overwrite the file. You say no, which causes the whole copy operation to be aborted and leaves you with no option but to repeat the whole copy operation.
2. If you install programs often, every six months or so you have to reinstall Windows in order to get rid of the junk that tends to pile up until it gets unmanageable. Nobody ever considered the possibility of keeping the OS separate from the stuff that gets embedded in it afterwards.
3. You copy an installed Windows to another machine. It ceases to work.
4. Your Windows is installed on an NTFS partition. A small boot file gets corrupted and you completely lose access to your HD. (I faced this problem a while ago and the only way I found to get the system back & running, short of reinstalling Windows, was to boot with Knoppix Linux on a CD.)
5. Knoppix Linux boots from a CD in five minutes, recognizing all your hardware and implementing a GUI that is better than Windows. Windows takes one hour minimum, requires successive boots and still demands specific drivers for your hardware.
My point here is that (a) Windows is basically a dumb beast; (b) it won't get better because the architecture is flawed. Its success is a huge feat of marketing. What happens here – as we have been seeing for years with the successive irrelevant versions of Office – is that you get to a point where you can only embellish your creature, but it's still the same beast underneath. Windows has reached the baroque era – oh, what if we add a cute little dog that waves its tail to the user and call it "user-friendly"?
Given the huge resources it has, Microsoft could certainly come up with a better OS. But Microsoft, like Bill Gates, is humorless – and humor, as we all know, is a side effect of creativity and intelligence. If you ever tried to read the cryptic help files of any MS product, you know what I mean.