The First Amendment of the United States Constitution states that "Congress shall make no law... abridging the right of the people peaceably to assemble, and to petition the Government for a redress of grievances." The United States Government now makes the use of so-called "Free Speech Zones" to restrict the peaceable assembly and petitioning of American citizens.
Those who go to see the President speak, including the media, generally do not have an opportunity to see the protesters — they are kept safely out of the way, out of sight.
This was not the way it was meant to be. In our system, where everyone has a voice, anyone should be able to protest within full view of the President and his supporters. They should be able to hold their signs up high, proclaiming for all who will listen what they consider to be right. Our country was not founded on the basis of excluding voices, it was founded on the basis of including and protecting everyone's voice.