Oh to go back to that 486 with the Win95 platform. It's gonna go down as the Model T, the DC-6, the Zippo lighter of computers. I had that sucker running for years and years, with nary a problem.
I think people upgrade the entire deal because a) in the past just upgrading the OS didn't work all that well, if at all, and b) they don't want the new OS, they could care less about the new OS, they want the hot new graphics card with the amount of memory and clock speed to handle it.
For myself, and this is about WP programs to begin with, I would never (nor would almost anyone not publishing some newspaper or mag) need anymore WP power than that (486/95) had in it. I wrote my thesis, dissertation and did my graduate record exams on one, it was fine.
It was really the gamers and graphics people (digital photography included) that drove everything since then.