A simple question: How does killing him stop the planned attack? As far as I know, being a general and all, had people working for him that did all the actual attack stuff. So, once he’s made a plan, the plan can go on just fine if he is taken out of the equation. Yes, it means he can’t plan another attack tomorrow, but today’s attack is still a possibility.
I’m guessing Soleimani planned attacks pretty regularly over the last few decades. And that makes him a bad guy — if you’re us. But during World War II, General Patton planned and saw carried out a whole bunch of attacks on Germans. If you were a German, you probably thought he was a bad guy. But if the German’s had managed to get a V2 into the middle of American headquarters and killed Patton, would we have lost WWII? I don’t think so. Maybe it would have taken a little longer, but I’m pretty sure we would have still prevailed.
Back in the Bush years, I can’t count the number of times we “got the number 2 man in Al Qaida.” There’s always a number three man ready to go. These assassinations don’t seem to be that useful for winning wars.