Basic elements in games such as story and gameplay dont change. Mario still jumps, link still solves puzzles, gta is still an open sand box and FF still tells a story about saving the world. If you look at it that way, games are still just games, even though they seem to be a bit more like movies nowadays. This enables classic's to still be relevant and interesting 5, 10 or 20 years down the line, becuase they're gameplay and stories are superb and not so different to what we have nowadays if you think about it.
Some gamers have trouble appreciating these games due to the graphical gap, but I still think DKC and FFIV and Chrono Trigger still look gorgeous to this day.
