Well it's really a point of view thing.
When Vader/Anakin said his last words the meaning is different for me. ("the truths we cling to rely greatly on our own point of view").
Really it all boils down to how each individual takes this information and molds it in their mind. There's no right or wrong answer unless Lucas finally tells us for sure his reason... so like I said before, maybe Lucas wants us to figure it out rather than him telling us.