Unless you're talking about removing humans from battlefields entirely, then that issue will always be with us. Britain and France lost a generation each in the trenches of WW1, along with who knows how many scientists, engineers, artists, and others. In the case of the USSR and WW2, though, it is arguably more reasonable: when Guderian and von Manstein are driving tank armies across your agricultural and industrial heartlands, a certain sense of urgency about the situation might not be a bad idea! It's impossible to predict which scrawny conscript might turn out to be a concert pianist, and it doesn't matter - if you don't stop the panzers, the only music played will be Wagner, forevermore. So while the waste of human potential then was huge, and appallingly tragic, I can't actually blame the USSR for dealing with the existential crisis they were facing. And let's be honest - if there were invading armies blitzkrieging across our own countries, how many of us would fight even if we were told "Nyet, you are a promising young writer! Too valuable to risk!"? The temptation would be very strong to ignore officialdom and find a way to be involved anyway.