Cutscenes which can effect multiple players should be kept short, which is why the MSQ ones are terrible bad and the devs have learned from them. Those short ones don't effect negatively effect repeated runs by much. The MSQ cutscenes are bad and the devs should have trimmed them and removed the pointless ones.
Its good manors to let people watch the short cutscenes in peace because the extra 10-30 seconds gained be trying to get the fastest time isn't worth much. If an extra 10-30 seconds is that important, you need to chill out and relax a bit.