chicken or the egg. Hardware companies do upgrades, and it is up to the software companies to choose to write software to be backward compatible.
Something people need to be aware of is that Windows 8 was designed around having a touch interface. It is Microsoft's answer to the iPad.
Microsoft does something that Apple doesn't. It actually tries to stay backward compatible as much as possible. Apple can care less about the past and even a relatively minor upgrade like 10.8 to 10.9 will break a lot of things. Minor compared to 10.5 to 10.6, which was the final transition from PPC to Intel processors. Then from 10.6 to 10.7 all PPC programs stopped functioning.
Something to note is that MS XP vs MX XP 64 were so much different that a lot of hardware never had drivers written for the 64 bit version. Not so much an issue with Windows 7, which is why I strongly recommend people that wish to have 4 GB or more of memory use Windows 7.
That all said, I agree with Redsky. I work in IT and we're about 50% Mac and PC and I spend more than 80% of my time working on Windows PCs than I do on Macs. Just about all the users (90%+) also have linux machines they use quite a bit. Most of the issues with Linux are just install new software or printer issues.
Sure the computer you had back in 1990 would work fine for 99% of what you do, however, new hardware, faster machines, make it necessary to upgrade software as well just due to what I said first. Do you need faster? Well, as you acquire more and more data, pictures, etc, you need larger storage. Larger amounts of data means your computer spends more time sorting, redrawing, etc. I remember working with a 2500 x 2000 x 32 bit color image on a 486 machine and it would literally take several minutes to just shift the image on the screen. Now we work with even higher resolution pictures with no delays at all.
