Will needed whipped into shape. As XO, its his job to ensure that the Captain's orders are carried out--he can raise concerns and questions in private, but once the order is given he has to make sure its followed. Just because they have a clash of personalities is no excuse for acting like a spoilt child, especially with the very real prospect of war looming.
Jellico merely showed another form of command that is a bit stricter and more formal than Picard's, nothing wrong with either of them. And if it wasn't for Jellico, we'd still be suffering Troi in those awful jumpsuits.