Megaman II was the very first action game that I beat in a single sitting. I went to my friend's house on a Saturday afternoon, plopped down and went on to destroy the thing over the course of a few hours, winning with who knows how many lives left.
I found the argument to be pretty persuasive in general, but every time I saw the name Megaman, I thought come on, what kind of person would need an easy mode for that game!!?
Ninja Gaiden, on the other hand frustrated me for the better part of a summer. It desperately needed an easy mode. That game is to Megaman as Megaman is to You Have to Burn the Rope.