Because when you kill 300 people, 400 people, who have nothing to do with the provocations Hezbollah staged, but you do it in effect deliberately by being indifferent to the scale of collateral damage, you're killing hostages in the hope of intimidating those that you want to intimidate. And more likely than not you will not intimidate them. You'll simply outrage them and make them into permanent enemies with the number of such enemies increasing.