Of course I'm not "argu[ing] for Kirk and Spock to be more vengeful." I've said repeatedly that I'm not happy with that ending. But I'm not going to be childish about it either. I may not care for it, but I believe a case can be made that it wasn't as bad as it seemed. And it's really pretty naive to assume that the way Spock felt toward his own mother's murderer
just a day or so after she died in front of him is somehow going to be typical of his overall moral stance toward violence in general for the rest of his life. Obviously that's a special case. And even if we think he was wrong to want vengeance, which I do, we should be able to sympathize with the reasons for that lapse. As Surak would say, "the cause was sufficient."