We've been watching Ken Burns' THE VIETNAM WAR, on the heels of (re-)watching THE CIVIL WAR. I think the problem goes deeper than hero-worship.
First of all: There's a tacit acknowledgement that every human society requires a fighting force at the ready. This is probably a practical truth of humanity: if you've got territory, you can bet at some point someone else is going to wander in and want to take it from you. As nice as it would be to think you could say "Hey, no, we were here first, could you find yourselves another chunk of land?" we all know that's not going to happen - or at least, it's not going to happen often enough. So we build the military into our societies, and use words like "deterrent" to convince ourselves we're not really asking for a percentage of our population to die for the rest of us.
Secondly: Humans seem to have a deep need for ritual. I was struck, watching the Vietnam documentary, by the kid they profiled who was so deeply moved by Kennedy's call to perform public service that he essentially blackmailed his parents into letting him join the military before he was 18. He had this deep need for manhood, for significance, for his life to mean something profound, and a long history of military stories (his mom talked about reading Henry V to him when he was little) prepared him to see military service as a way to become part of a noble brotherhood. There were people like this profiled in the Civil War doc as well - young men who articulated a deep need for connection, for adulthood, for meaning. And there's the military, ready and willing to take them, and our society, with its need for a military, perfectly happy to afford them that heroic social status so we don't have to stand up and do the dying ourselves.
I don't mean to trivialize any of it. I'm not military myself, nor are my parents; but they're both army brats, and three generations before them were career military (probably more). I live in a community with a lot of military families, and many of my friends - not just men - have served or are currently serving.
But yeah, fundamentally I think insisting that soldier = hero no matter what (until someone screws up, and then somehow they're the lowest creature imaginable) is dehumanizing and ultimately trivializing of what we ask our military to do. There have been wars that had to be fought (I think of WWII) and wars we should have known better than to start or join. But when we turn our soldiers into Others of any stripe, we're trying, I think, to shuck off our own social responsibility for the military decisions made by the government we elected. My daughter's got a friend whose dad is currently deployed; I'm not there with him, and I didn't give him the assignment, but I voted in elections that produced the politicians who chose to send him there.
We're all, as a country, responsible for that soldier's assignment. We're responsible for what we ask him to do, and its effect on him, and on the country he's deployed to. It's true that I, as a single individual, can't do a damn thing about one soldier or one military action or one war. But I do think talking about soldiers as selfless heroes rather than just a bunch of ordinary people allows us (in aggregate) to think less critically about our country's military strategy.