Technically Aizen did himself in from the very start.
I mean, he claimed to have knew Ichigo since he was born, set up all his battles, conflicts, power-ups, etc…...so why didn't he just eliminate the threat and/or impede his progress? Using him to "get strong enough to awaken the Hogyoku" is a dumb excuse, seeing as how Aizen didn't start using the lolgyoku to fight back until Ichigo was the only opponent left in his path.
He cut down Soifon, Kyoraku, Hitsugaya, Komamura, Rose, Love, Lisa, Kira, Iba, and Shinji all by himself, and used Wonderweiss to tackle Yama.
So you know.....I don't get it.
EDIT: Oh wait, Kubo's stupid reason that Aizen wanted somebody to be equal to his power. Never mind.
Equal ? Didn't he actualy write that he "wanted to be weak" ?