Compared to the SNES the NES hasn't aged that well in my eyes. It's like why would I want to play Metroid when Super Metroid is right there. Same thing with Zelda. I'm not saying that the NES is a bad console but it is a product of it's time.
For me personally once I moved on to the Super Nintendo it became hard to go back to the NES. The SNES improved a lot of the issues I had with the NES so for me trying to play NES games feels like playing beta versions of SNES games.
DuckTales is just as hard now as it was back then.but still a great game as for Ghost and Goblins I just don't have patience for that ballbuster of a game. Give me Super Ghouls and Ghosts instead