The basis of all the hate is that he's an overated player to begin with. Always has been. No need to up his numbers in Orlando, we saw the games, a supposed "superstar" and "MVP candidate" without a post-move. Anyone who grew up watching the likes of Olajuwon, Ewing, Robinson, Shaq, Mourning and them can't really respect Coward as a player. Like breh said, he's a glorified Kevin Willis. Good second-tier player that got overated due to the lack of interior play in the NBA in his prime, and the fact that Orlando didn't have any other "superstar" makes people believe HE carried them to the Finals.
Now if he wans't portrayed as a top player back then he wouldn't even get half the hate, but somehow he was presented (and presented himself) as if he should be in the same conversation as the Kobes, Brons, CPOs of the league, which is absolutely ridiculous.
Plus, for a supposed "Superman", dude's always bytching on the court.
All the other stuff came on top of this, but the real reason (for me, anyway) is that he's always been vastly overated.