I actually felt the opposite about Revenge of the Sith. Watching that movie for the first time was definitely an emotional experience, even thought I had known the outcome of it from day 1. Seeing the Rise of the empire and the execution of order 66 was very moving stuff. A viewer watching them in episodic order would be downright shocked and staring in disbelief that the so called hero of the story would fall so hard. Prequels can work.
Everybody knows that eventually they themselves will die. Does that make the journey pointless?