Israel has absolutely crossed some lines. And Israel isn't "wiping out everyone in Gaza"....not even close to it. Unfortunately, when you are fighting an enemy that has stated that its goal is to murder every single Jewish person in the area, and that has acted on those intentions with devastating consequences, that enemy (in this case, Hamas) cannot be allowed to continue to exist in any meaningful fashion. Hamas knows this, which is why it deliberately uses schools, hospitals, universities, apartment blocks, etc to conduct military operations. The best thing for Palestinians at this point would be for Hamas to cease to exist. Unfortunately, that isn't realistic, but Israel has substantially weakened them.