I completely understand what you're saying, but I disagree.

See I always looked at the Star Wars series as being purposefully out of order. 1-3 comes first, but they give you 4-6 first, so you're surprised by something that normally wouldn't be a twist. Then, afterwards, you go back and see what they didn't show you, the first three episodes in which that twist is developed and explained.

I always saw the prequels as "how Luke's father became Darth Vader." It was, to me, all about explaining the twist. So "preserving the secret" just doesn't seem right to me.