Why didn't the Worldmind select the Planet Sakaar survivors?
Didn't they go out of their way to establish that the new Nova Corps is founded, to some extent, on how easily the Worldmind could manipulate them? The Worldmind has a very specific carrot and a very specific stick, and if the Warbound didn't like the carrot, the stick wouldn't exactly work.
Also, Greg Pak seems to be the only person using them at the moment.