I hate characters that are angry all the time. If they aren't a Sith Lord, they have no reason to be all pissed off 24/7. Jaina needs to calm down, and listen to Varian, or Anduin.
No...she doesn't. It's fine for her to be angry. She has every right to be. Theramore was her home for years. She was responsible for it's people and their safety. Saying to have all that wiped out in an instant by the mana bomb was devastating to her and she has a right to seethe with righteous indignation.
Hell I want more characters like Jaina. People who realize that you can't make peace with everyone out there or that fighting may be the only valid answer. Right now the only way to end this war is to take out Garrosh(and possibly Sylvanas) as well as cripple the Horde's ability to make war. People like Anduin, don't realize that, and subsequently when they try to implement their own peaceful plans wind up paying for it in spades.
There is a time for talk and a time for fighting. This is a time to fight.
While I agree that disorginized hippees shouldn't run wars, Jaina isn't being rational with her anger. When she gets angry, she just flies off the handle and attacks any enemy without thinking of the consequences of her actions, just like Garrosh.