That's true about friendly countries @warren. Right now we're seeing shifting alliances and baiting between the US and ostensibly "friendly" countries, and cozying up to "unfriendly" ones. But I don't make my judgements based on which country I was born in - I make them based on the circumstances and my ethical considerations of the issues. "My" country isn't always right just because I happened to be born in it. If the US were to attack the UK unprovoked, I would be on the side of the UK, and vice versa. As far as economics, trade wars, sports, spies etc., I don't see why it matters who I root for. Unless I were a spy, a policy maker, a global capitalist, or a sports star, it's not going to make any difference to anybody.
I think you're right, @aldecaker - it's just one of those things that resonates on a deep emotional level for some people, while others just don't get it.