Pledges are proclamations of commitment. I don't believe that any oath or pledge means anything unless there is some sort of accompanying action that separates those who swear the oath from those that don't. Recitations, no matter whether they are in fraternal, educatonal, military, or other organizations are mere words until there is an appropriate action.
Most of the people who recite the pledge don't give a rat's butt about adhering to the Constitution, so what good is it? What does it prove?