Very very very strange list,
Zelda II was one of the first games ever I played all the way through. I only played the first Ninja Gaiden and that one I consider far more easy than 90% of the Mega Man games. Kid Icarus is IMO a lot easier than Metroid however harder than both Zelda II and NG, and they're not even on the list.
Beware, I live!
I am Sinistar!
Beware, coward!
I hunger!
Roaaaaaaaaaar!