Hello!
I believe that the purpose of this excerpt is to inspire. The word choice of the author (urged, ponder, rise to the challenges, etc.), help to give us some insight into the purpose. The excerpt leaves you feeling empowered and encouraged to "rise to the challenges," as Pat Mora says. While it may seem like at the beginning the author is warning the audience, when they say "we will continue to squander our talent if our leaders... do not reflect our grand variety," it goes deeper than that. Mora isn't simply warning the audience of what could happen, but rather aims to inspire students (and any other readers) to try to solve the issues facing us as people, particularly in terms of leadership.
Hope this is helpful, please let me know if there's more I can hep with!