That's how I've always felt too. It became Anakin's story when really he should have been a smaller part of a larger story, with Obi Wan as the protagonist. In any case, because of what we already know from ANH, Anakin needs to be/have been Obi Wan's apprentice, and if preserving the ESB reveal has any importance, there's absolutely got to be a (at least implied) 2nd apprentice who could conceivably be capable of turning evil.

Ady's certainly got his work cut out for him, that's for sure.