He did pay. He was penalized in the context of the game. He received a 5 minute interference major and a game misconduct. He already got what he deserved based on the rules of hockey.
The debate here is whether there was purposeful intent to injure, which is where suspensions come into play. The NHL ruled that Chara did not purposefully intend to injure Pacioretty. Some agree with that and others don't.