They drove me nuts too. But seeing as how this was the first MM game I actually owned, and I was only a seventh grader, I played it with persistence. And my brother and my friend always pressured me into beating it again. I would always yell when a boss would kill me.
I later bought MM1 used when I was in high school, but could never finish it without the Game Genie giving me infinite power. Yes, that one-eyed rock monster is really hard.
I borrowed MM4 from a friend when I was in high school, but never could have finished it without infinite weapons. When you fight Dr. Wily for the last time, only Pharoh Man's weapon can hurt him. If you run out of that weapon, you're screwed. And the ending of this game waw really lame.
I have still never completed MM2, and that's the only MM game I still a copy of!