I think after spending many many hours as a youth listening to music played on a synth with a particular character and range of timbres (while playing games) you become inured to it.

Music made using that synth just sounds particularly pleasing.

I didnt have a nintendo (so these demos dont really have that effect on me) but I did have a C64, so any music made with the sid chip seems to sound better to me than it ought perhaps.