How to be a decent GM
I do your "Carebear Alternative" all the time. When a player asks to do something stupid, I say "are you sure?"
I think I've heard about an ability from an RPG game somewhere called "Common Sense" that's basically the "Carebear Alternative" as a game mechanic - it requires the GM to inform the player when he's about to do something stupid.
Oh yes, I did see that ability in a few games. Sadly, it usually costs aptitude points that most players prefer to spend on other, more useful powers. But by any mean, go ahead, give newbies that ability for free!