I’ve seen someone say it before (I think it was wormmonrebirth), but now that I’ve seen more seasons of Digimon, I really think it’s true: 02 seems to be the only season in which the Digidestined/other term depending on season actually really and properly struggle with killing Digimon. Specifically, they mentioned that some people considered the 02 Digidestined weak because they struggled with killing Digimon more than any of the others ever did.
In 01, they didn’t like it, but they sure did it pretty quick, and in Tamers there wasn’t much hesitation that I remember, and they don’t even think about it in Xros Wars/Fusion.
The protagonists in each season have differing reactions because they’re all different people. Taichi, for example, is the kind of person who will do something he doesn’t like if it will help his friends. Daisuke thinks all life is precious, and hates the idea of ending it but will do it if he has to to protect everyone else. I don’t care to describe Takato (I never enjoyed Tamers). And Taiki? He doesn’t think about it, if he can help someone (even a jerk), he usually does it with no more thought than required.