Me, I'm with Geschosskopf. I don't see why having life support is a good thing in the vanilla career. If you want something realistic, try a real time game to the moon, or to orbit without warping. Takes a good solid ten minutes. I don't want a simulator, I want an arcade game, a bit of fun. Not worrying about kerbals dying from lack of life support. Not worrying about whether or not you packed enough support for your stranded kerbal on the moon. If it did happen, make an option to disable it.