You have to die a lot to activate this feature, so it's fine with me, especially since it won't get you the secrets or anything, and will relieve a lot of frustration. I mean, I don't know how many games I shamefully stopped playing because I couldn't get past this one part after trying for an hour or two. You can make it challenging, sure, but let me get past a super hard part if I've been trying for a while and just want to continue on with the game.
SMB2J? If it's the game I'm thinking of, God, I sucked at it. I should try it again, now that I'm not playing on an HDTV, though. I think it's just a case of me sucking in general, but you never know.