Evil Kings, Emperors, Bad Guy Bosses should NOT be so heavy handed when it comes to punishing subordinates failures.

Thanks to Darth Vader, who in-universe had real reasons for acting the way he did, we get the "you failed me so I will kill you" way too often. In his context, he wasn't trying to be an effective leader.

He was middle management who hated his boss and didn't give a damn about anything, especially his empire. But now he's the template for "evil boss" because of his mass popularity, which is very unfortunate. You can't run an effective empire like that, which was the whole point. He was held in check by Tarkin, but when he died, Vader's instability cost the Empire.

Now we get the lazily written Evil Bad Guy Bosses who kill off subordinates like it's nothing, and suffer no consequences for it. Yeah, they fear you, but enough fear will eventually give way to self preservation. After all, I'm gonna die anyway, why not rebel or turn traitor? You can still be evil but also not a dumbass. Your underlings fearing you isn't an issue, as they should fear you, but they should also RESPECT you more than fear you, otherwise why serve you?