Bingowings said:
To really feel sequences like that jeopardy has to be there.
You can't feel concern for something you have no emotional investment in.
I think that's the problem with the PT. Any emotional investment had to be supplied by the viewer because we already knew who the characters were.
We were supposed to care about how Vader came to be because of the OT, not because we actually gave a crap about the characters in the prequels. They didn't earn it. Lucas was so wrapped up all the stuff he couldn't put into the OT (which the films obviously didn't need) that he forgot to make a good film, with interesting characters and performances regardless of if someone likes Star Wars or not.
Another thing that hurts the prequels is that by making dumb story choices like Vader building C3-PO he makes the films smaller in scale. Jedi feels bigger than the PT. The opening of Star Wars feels more epic than the climax of Sith. You really do feel like this is a tiny planet in the middle of nowhere, and the scale of the Star Destroyer and how it's introduced really sells the power of the Empire.
On a more general note, the fact that a film is successful enough for there to be a prequel automatically means it doesn't need one.