The only thing I can say in defense of MoS is that up to that point he hadn't really been pined to the limits of his power or his moral teachings. He never had to deal with an adversary that could do as deal out as much as him so he never had took into account how much destruction and potential injury/death his battle could end with. Up to that point he was hiding and taking opportunities to save people as they came up but never on that scale or under those circumstance.
Not unlike soldier who have never been in combat. Imagine and train all you want but until you're in the ***** you're never truly prepared for what you're capable of or what the consequences of your actions may be.
Terminator Salvation I won't defend as much. The time line was pretty vague, but I would definitely question where they happened upon things like A-10s and even helicopters after a nuclear holocaust. They refer to it as bombing back to te Stone Age for a reason.