IMO, Building a PC has been easy mode since SATA was adopted industry-wide. Not necessarily because SATA marked the most difficult part, but it fixed the last remaining standard that gave new users issues(Ribbon cables and primary/secondary/master/slave). Basically 2004-ish. I honestly can't think of any new standard that has made anything truly easier since then, only subjectively better from an ease of construction standpoint. USB 2.0 was around, signal on wake plug in play standards. XP was finally user friendly for hot swapping compatible expansion devices. IMO, the only argument might be wireless networking, but that had more to do with pre draft standards mixing into chipsets and being sold as something that didn't really reflect the capabilities of the chipsets. As you could have easily bought good network components and has no issues.
The one thing that I would say is actually harder, is finding a brick and mortar store that sells nitty gritty components that aren't just some china clone crap. If you went to best buy or circuit city, you could actually find top-tier fans, thermal compond, cables, etc. You could find decent stuff at office depot/maxes. Now you go to best buy, hah, they sell some knock off crap that works, but for the same price as a top tier component that performs better. Unless you live in striking distance of a Frys or Microcenter, everything has to be internet only.