I attribute this to 2 things. First, games now are all 3D and take 8 or 9 hours to beat and also lack of coop games that you can play with friends. Every single game has all these options and 3D gameplay, but they're not as fun and easy to learn as an original 8-bit platformer.
The beauty of 8 bit games wa they were so easy to get into and figure out. You didn't have to look at the manual or sit there for 20 minutes learning the buttons. You could go in, a does this, b does that and just start playing.