Ah could be because Kei is an extremely attacking player despite his height, while Boredo is the epitome of a pusher: his whole game is pretty much getting the ball back in play.
Not to mention being a jerk doesn't qualify as having personality. His disgraceful antics have not been forgotten ie Barcelona final vs Gaudio and Hamburg semis vs Ancic.
What does his height have to do with anything? Since when did being under 6' automatically merit a passive style? There have been many powerful and flashy players in history that have been short. Look at Rios, Agassi, Grosjean, Nalbandian, Ilie, Coria, Clement, Benjamin Becker, Arazi, O. Rochus, Puerta, Davydenko, Costa, Corretja etc. and even the likes of Hewitt could/can play aggressively and approach the net with certainty.
Robredo's whole style is not pushing, that's utter nonsense if I've ever heard it. Just because a man doesn't possess lots of finishing power doesn't mean he's a pusher. He approaches the net far too much to be considered a pusher, for one, and he tends to go for the lines often on anything that's not within a couple of feet or so of the baseline on his forehand as well as possessing a good drop shot. I don't even like him much at all, but he's far from a pusher, especially when your judgement of attacking tennis is pretty lenient considering your comment about Nishikori of all people playing "extremely attacking tennis for his height".
Personality good or bad, he has one.