Quote Originally Posted by Roshi View Post
He doesn't want to be in Yamamoto's position (Yamamoto still has to answer to the central 46)... He wants to be King of the Soul Society, which he couldn't do by following the Soul Societies rules.
However Yamamoto holds the key to that particular door. Aizen wouldn't have to circumvent the existing key by killing all those people if he could simply get it from Yamamoto...