Apologies for replying to my own post, but the more I think about it something else occurs to me:
Back in my ZX Spectrum / BBC Micro gaming days, the availability of games was lower than it is now; I remember playing games to death simply because I'd spent the time and effort going down to my local WHSmith and forking over the £10.00 for a cassette. The other factor was the time and effort required simply to play the damn things; remember how long it took to actually load the game into your home micro from tape? Fiddling around with the head because the damn thing would fail to load after 10 minutes of waiting?
Nowadays, gaming is so instant and available that there isn't the compulsion to stick at a single game and see it through to completion