the advancements we have made in killing each other
Actually maybe this is a sign of changing values, these devices are designed in part so you don’t sacrifice lives. And of course these are likely to be attacking the oppositions robots rather than people, it’s not as if everyone else isn’t developing such weapons. Winning a war is largely about occupying and holding territory to deny it’s resources to your enemy. In Vietnam the US just concentrated on trying to kill as many Viet Cong as possible. Operations were launched that were no more than raids, they didn’t hold the ground they’d cleared troops from. Time after time they lost men to take a position only then to withdraw. I guess the point of these weapons is to be your assault force with troops following to secure and hold an area. Far better to defend an area than attack it if you are trying to keep casualties to a minimum.