This was almost certainly not an assassination attempt. As you point out, it was a deeply embarrassing penetration of what was assumed to be a highly competent Russian air defense system, and it seemed to have a crushing effect on the "big parade" shortly thereafter.

Every Russian attack on Ukrainian cities makes me feel the way that you do, bomb the hell out of the Russians. Probably not a smart move...every Russian attack probably stiffens the Ukrainian resolve, need the Russian people to feel just the opposite.