If adults want to swear allegiance to a country or flag, that's their business. Forced rote indoctrination of children who can't possibly grasp the meaning of what they're being coerced to pledge 5 days a week X 13 years of school is inappropriate for any country, particularly a non-totalitarian one. Other democratic countries don't feel compelled to do this and they manage to have patriotic populations that love their country.
The US isn't the only country whose military have fought and died for their country. That's been true of most, if not all, nations on this planet. Hollywood depictions aside, in proportion to their populations, virtually all European countries (as well as Australia, New Zealand & Canada) suffered far greater losses of life and limb in WWII than did the US.
Don't get me wrong. I'm happy to be an American and love many things about this country. However, like everything I love, I'm willing to be honest about its failings in hopes of making things better. I had two Chinese HS foreign students living in my home for two years. Their unquestioning loyalty and belief in their country and its leadership was something to behold - and I don't mean that in a good way.
"Blind faith in your leaders, or in anything, will get you killed." Bruce Springsteen