Apparently you can't answer a simple question. Do you really think anyone who was actually involved is happy with the results of that particular day at work? You seem to think what happened is fine, justified, etc., etc. But I'm pretty sure that they guys who were there doing the shooting aren't feeling the same way. I'm pretty sure they'll see that little kids face for the rest of their lives, and struggle to get over that day.
But in your mind nobody needs to improve their tactics, or learn more because they are already experts. Why don't you call up the guy who shot and killed a first grader and ask him if he feels he is an expert now.
Of course they’re not happy!
Are you freaking kidding me? You think that’s the issue?
The issue here is it’s not their fault.