I just got a new desktop this month - faster CPU, more ram, SSD, etc - it really is a lot faster than my 3 year old one. So I don't think hardware improvements are an issue, computer speed is still increasing heavily, and dropping compile time and allowing more programs open at once is always great.
However, since I built the PC myself, I could choose what OS to install, and I'm using Linux and Win7. If I was a more regular user, I'd be forced to use Win8 - and if that was the case, I would not have upgraded. If this is true for other users, then it's clear to me that Windows 8 really is to blame here. I would certainly not purchase a computer running Windows 8 for desktop work, and I believe a majority of desktop users agree with me.
"So I don't think hardware improvements are an issue [...] dropping compile time and allowing more programs open at once"
for you. I doubt that "compiles much faster" or "allows more programs open at a time" would be marketing slogans that sell zillions of PCs. 'Normal' users run a web browser, maybe an email program, and Wordpad (I am not even sure that is an exaggeration, nowadays)
Also, about the SSD: in my limited experience, the only thing it really speeds up is boot time (shutdown of my iMac now takes ages, relatively speaking). Launching programs probably doubles in speed, too, but it already was fast enough for me. If you are compiling C/C++ or launching a VM zillions of times a day the difference will be huge, too, but [see above]
However, since I built the PC myself, I could choose what OS to install, and I'm using Linux and Win7. If I was a more regular user, I'd be forced to use Win8 - and if that was the case, I would not have upgraded. If this is true for other users, then it's clear to me that Windows 8 really is to blame here. I would certainly not purchase a computer running Windows 8 for desktop work, and I believe a majority of desktop users agree with me.