I started to think about the Courage / Stupidity ratio. Right now it has no impact of the game, but will probably later. My way to see it (in a Kerbal way) :
Case 1 : Perfectly stupid coward (courage = 0, stupidity = 100). That one is afraid of anything, but don't understand how things works and will probably capable of pressing the buttons "just because they look cool". Also very naïve "Do that, you risk absolutely nothing, I swear" - BOOM ! -. With catastrophic issues.
Case 2 : Smart coward (courage = 0, stupidity = 0). That one is also afraid of anything, but also understands what is going on. So he will probably do nothing, but his chances of survival are better than case 1. Quite rebellious to orders "I don't want to die !!!", so little value.
Case 3 : Stupid hero (courage = 100, stupidity = 100). That little guy will throw himself eagerly in any sort of troubles. Like he has no idea of the consequence of his actions, he does stuff that looks cool to him. Life expectancy expected : VERY short.
Case 4 : Smart Hero (courage = 100, stupidity = 0). That one would probably be too smart. He is ready to throw his life away, but won't accept an order that seems stupid to him. Smart enough for self-preservation, will give his life only if HE thinks it's a noble thing.
Case 5 : Balanced Kerbal (courage = 50, stupidity =50, just like Jeb). Probably the best Kerbonaut. A moderated courage ensures basic self-preservation instinct, but still allows him to perform reasonable stuff. A moderated stupidity means that he will obey orders with a decent proficiency.
:2cents: