I think some of the reasons the older systems have so much appeal are:
- Less is more.. The experience is not as 'perfect' as it is today. As with Film Noir, Horror Stories (or anything written for that matter), the less detail you present visualy, the more your imagination fills in the gaps.
- I was a teenager when I was playing with these systems so my imagination had not been as jaded by the big bad world by that time.. It was easier for me to get lost in it all. So in a sence, playing the games reminds me of the way I used to feel, even if I don't feel it so much now.