Even with each machine's contemporary software, old stuff is still slower. Windows 98 is contemporary for my 1Ghz P3, Windows 7 is for my 3.3Ghz i5. It's not just clockspeeds at the CPU either - faster buses, solid state drives, better code, more hardware optimisations in the software.
There is always the nostalgia case, but in terms of practicality, usability and user sanity, most of it is just old hat. Frankly speaking, I'd apply the same logic to most classic cars and audio equipment too. If I have a component break on me, I can source a replacement within a day for a reasonable price. If the cam shaft on a 1963 Mercedes breaks, you're shit outta luck - and that isn't practical.
