Jokinen has turned into a bust and I think Sutter just wanted to dump him. But he's a UFA at the end of the season. Sutter is desperately trying to make the playoffs, so he's shaking things up. But if Kotalik and Higgins don't work out either, he's got longer contracts to move, which will more difficult, and the players aren't stars so he won't get that much interest.
For Sather, obviously Kotalik and Higgins weren't working out. So he's able to dump their salaries and contract to free up cash to sign some UFA's this summer.