The hatability of Seattle comes from:
A) The bandwagon fucks who didn't even know the team existed five years ago and are now shouting "WOO 12TH MAN BABY, BEST FANBASE IN ALL OF SPORTS YASSS" at everyone else.
B) They seem to have the flag dome (like Kuechly has a flag shield, except the entire team) over Seattle and the blessing of the league and any residual hate for Uncle Rog gets passed onto his favorite son.
Besides from that they are threatening to become the first true NFL dynasty since the Cowboys. And hating dynasties is as American as apple pie. That might not mean as much to you as a Steelers' fan, because your team has 33 championships. But to us fans of little franchises that don't have shit, there is a slight element of jealous resentment, I won't lie.
EDIT:Wussy isn't hateable. He's out here playing a role and getting money and increasing the brand for it. I don't like playing against him because he pulls the wildest shit out of his ass at the most inopportune times, but I don't hate him as a man for how he conducts himself off the field.