Why aren't all military aircraft equipped with ejection seats?

C-130, C-17, C-5 and many other do not have ejection seats. With an aircraft with such a payload it wouldnt even noticed they were there. The C-17 crew who stalled and crashed in Alaska not too long ago could have benefited with this by their lives. All other crew sush as the load master could have an ejection seat as well. He could be in it for take off and landings and when not in it he could bail out or revert back to his ejection seat.