I don't find it very persuasive to simply assume that the casualties are "excessive." Whether they are actually excessive is really the whole issue. As of right now, there is no strong evidence that I'm aware of that the injuries from today's attack are "excessive" much less those of a different purely hypothetical attack.
And even then: to judge whether casualties are excessive requires an understanding of the goal to be achieved, which is almost completely absent from this discussion.
And even then: to judge whether casualties are excessive requires an understanding of the goal to be achieved, which is almost completely absent from this discussion.