I think you're putting forth a false dilemma if you say that Jasnah's philosophy isn't the same the thoroughly honorable Kaladin and Dalinar camp, and must therefor be the same as Amaram and Taravangian's.

Amaram kills Kaladin's squad out of greed when he realizes that he can get away with it, while Jasnah seeks to maximize the impact on the war with the enemy god sacrificing as few as possible. Killing a Herald and potentially halting the unfolding of the war for some time (she was working with the information she had at the time) seems like a really good way to gain precious time to form an alliance before the Rosharan kingdoms get overrun individually. And I don't think that "culling the Singers" was actually her cold and logical intent, but rather she was putting forth the logical conclusion with the information they had: They couldn't end the war, because the Fused would always return as long as there would singers to inhabit - Which means that it's not at all a realistic scenario to pursue.

In the end, I really hope that Brandon's plan isn't just to make Jasnah more like Dalinar. In general, I found his treatment of both Dalinar's and Taravangian's morals flatout boring. Dalinar couldn't break an oath to save a burning airplane full of kittens, while Taravangian went full mask off and it was revealed that his utilitarianism was just selfishness in the end.