It's not that difficult. Insert DVD, next-next, done. With a Mac, perhaps, it's even easier.
occasionally you get a missing graphics driver but windows update just pulls a WHQL driver.
As for recovery DVDs: these are the first point of call usually and are pretty good generally.
there are many paths and they are all navigable by an average user.
I think though that although some people will reinstall their system (why?), it should not be needed and that's where we are growing to with, on the low end, tablets (mostly linux: android)/chromeos (linux)/windows laptops and on the higher end macbooks. These machines get thrown out before a reinstall would be needed by the less computer savvy (and even by the computer savvy who earn too much :).
In the mac space people buy a new macbook / iPad when the new shiny upgrades are announced (october?) and on the other end of the spectrum people abuse the stuff OR it gets 'too slow' and replace it. In between is the high end Windows market, which, so far, seems to be split between business users (which are more and more going tablet), high end gaming and geeks. And those three all do (or their company does) in fact reinstall / upgrade (hard and soft) their systems. But that's very far from 'most users'.
Granted I have had problems even recently with wireless not working out-of-the-box on linux systems.