We are a commune of inquiring, skeptical, politically centrist, capitalist, anglophile, traditionalist New England Yankee humans, humanoids, and animals with many interests beyond and above politics. Each of us has had a high-school education (or GED), but all had ADD so didn't pay attention very well, especially the dogs. Each one of us does "try my best to be just like I am," and none of us enjoys working for others, including for Maggie, from whom we receive neither a nickel nor a dime. Freedom from nags, cranks, government, do-gooders, control-freaks and idiots is all that we ask for.
It's not really about a flag. It's about "the Republic for which it stands." It's a way of testifying that you agree to the American social contract. In other words, "I agree to this deal."
Kids cannot know what that deal is. It's quite a serious deal, really, because it can cost you your life, plenty of your property, and some of your freedom. It's freely given, too, if you're old enough to give it. You can always move somewhere else. Tom Friedman can move to China.
I don't care whether Rousseau's social contract theory is valid or not; it's an essential concept anyway because it makes it clear that a conscious choice of citizenship is meaningful and important - even if secular and not sacred.
I changed the words I say years ago. Upon reflection pledging allegiance to a flag or even the Republic was not what I really owed. So I changed "flag" to "Constitution" and "to the Republic that is governs..." It also aligned it with my oath as an officer to support and defend the Constitution.
While unlikely, the flag and even the Republic could become unaligned with the Constitution, i.e., my pledge and oath do not permit my allegiance to some nation or government that discarded the Constitution regardless of the flag it flies.