Obi Wan was the main character of the prequels but they kept thinking it was Anakin. Messes up the framing of a lot of events particularly in the first movie. By the third one I think they figured that out, but it has plenty of other problems even though the narrative focus was better.
D and D had multiple 10 episode seasons to get it done. Lucas did it in three movies. (lemmy.world)
Anakin has a clear motive, and a logical progression from naive to evil....