I noticed the same trend for PCs in the last 20 years too. In the late 80s and throughout the 90s, things were advancing at a blistering pace. At the start of 1990, a common configuration was maybe a 20Mhz CPU and 16 MEGAbytes of RAM, and by then end of the decade, we broke the 1Ghz barrier and were putting 512MB-1GB of memory into our machines.

Yet now, I'm still playing recently released 3D games on a first generation quad core i7 from 2009 just fine (as long as nothing in the game starts spewing too many particles).