Well I mean in the case of V3 especially those were all super high stakes situations - or at least the characters believed the stakes were super high. I mean grant you, Korekiyo was an exception, but everyone else believed they had no other choice. Kaede killed to save everyone, and was hoping to end the killing game at the same time, Kirumi killed, and was willing to sacrifice everyone else to (she believed) save the whole world, Gonta killed to spare his friends the "truth", and Kaito and Kokichi's plan was to make the kill so impossible to indentify that the whole game was forfeit.

But that aside Kazuichi Best Boye and he is far more than just a skeezy grease monkey.