And FYI the US handily and clearly won the Vietnam war; the South Vietnamese insurgency was defeated and the North Korean Army was obliterated.
Due to political pressure at home, the US withdrew after the war, and a short while later the North Vietnamese were able to rebuild their army and waltz in and topple the fragile S. Vietnamese government. The Communists then murdered 10's of thousands of people in the streets and imprisoned 100's of thousands and of course enforced totalitarian rule which kept millions in fear and poverty.
Were the Americans to have simply left a contingent of soldiers in the South, thereby keeping the legitimate threat of violence, it's unlikely the South would have fallen and might very well look like S. Korea today.
To your point, 'body count' is not a very good number to use when you're fighting an insurgency where there are a lot of irregular forces who can come in and out of fighting, or where soldiers can be replenished (i.e. North Vietnam can recruit willy nilly on their turf).
But it's still a valid measure and though you don't hear about it these days (for PR reasons) you can absolutely be assured that all NATO forces meticulously con't how many enemy forces are destroyed, and that it is a 'target' on many missions.