Is he in the locker room causing problems? Probably not. In everything I ever saw, he seems like a really nice guy.
The players love him. That is the problem.
He's a leader by example whether he wants to be or not, simply because of his production in previous seasons, his longevity, and his contract. When he doesn't play hard or bother to work consistently for pucks or play defense, they notice. Hard to tell young players to play defense "or else" when they've seen Skinner get away with it for years.
EDIT: In my management classes they had a concept called "level setting". Reset your organizations expectations and then hold to those new levels. This is the NHL version of "level setting".
This right here is why he had to go. You can't have premium ice time being rewarded to someone who isn't putting in the effort. Why would anyone else work hard?