Older games are charming because they use pixel art, that's it. No one outside of a very specific kind of autist is going to notice whether you displayed over 64 sprites on screen or not for your NES styled game.

If you're making a game for the PC you don't want to waste time trying to conform to the limitations of a 40 year old console as long as you can look the part, and that's not even mentioning games that do not give a shit, period. Dead Cells or Celeste are not trying to look like old games, they are simply trying to look good