User blog comment:Xilinoc/Ch. 602 - Bane Licking Good/@comment-28861328-20141023151805/@comment-5657895-20141026083648

It's hilarious you question Yhwach's motives and you claim you want Aizen back.

What did Aizen ever want or achieve? His motives were just as unclear. In fact, half the time he was barely fighting for any real purpose. He was just... there. Hell, even the Fullbringers had more storyline reasons for being villains than him.

Yhwach was defeated in the last war and his entire race was decimated. Plotting vengeance makes sense actually.