The Pledge of Allegiance is not the Constitution, of course, so is not binding on anything. But the observation about whether "liberty and justice for all" is understood and truly accepted is the crux of the matter, it seems to me. So, is it allegiance to a mere symbol--the flag, which might mean many things, including American militarism and hegemony to some--or allegiance to actualizing the conception of individual liberty and justice: what I thought America was supposed to be about?
Growing up in the Cold-War 1950s the Pledge was part of the socialization of American nationalism instilled in young minds. It was a major part of the American identity set off in contradistinction to a very real expansionist Soviet bloc. My elementary school in far inland Kentucky had a civil-defense lookout on the roof, under Sputnik skies, apparently watchful for any sign of Russian missiles(!), while Congress and the media were embroiled in the Red Scare. So, the flag constituted part of an identity that was set off from a Communist-Red-Soviet enemy-other. We were Americans because we were not they. It is easier for identity formation to imagine an enemy.
Today, national identity is more difficult to acquire, as I watch my students recite the Pledge: now no godless communism, wars fought for manufactured reasons, and personal identity built on consumerism (the triumph of capitalism!). My modeling the recitation of the Pledge will mean little to nothing to my students as they are set adrift in a placeless world of mediatized reality. In a simulacrum world, to what does one identify (besides the consumer-self)?
My conclusion is that the "end-of-history" winning of the Cold War also means an end of easily formed American nationalism and identity. In the resulting vacuum political movements can exploit the loss. The Tea-Party movement, I believe, steps in to create imagined enemies to rally around the flag against. This time, enemy-creation imagines an internal ruinous, un-American godless, Marxist (as they see it) liberal-other; and an external Muslim-terroristic-crazed religious-other.
As I recite the Pledge five days a week, I'll think more of potential American justice and to what I should dedicate allegiance, while others look for enemy-others to help create their identity.