As just graduating college, I have seen so many people struggle to speak in front of people. It is such an important part of college and the working world, that people should learn it as soon as possible. It will undoubtedly help them in the future. It really is doing a service to them.
Speech and debate are for the public, thus it needs to stay a choice to those who want to take up anything having to do with public relations. Not everyone is gonna become some sort of politician.
Adding yet another class to graduation will clutter up a student's schedule and they'll have to drop a class from that may actually useful to them and their career goals
While advocacy, citizenship, and confidence should be endorsed at the high school level, I do not believe it should be a graduation requirement. Some students are naturally more outspoken than their peers, and it is these individuals we see in attendance of speech/debate clubs throughout our school system. It would be unfair practice to those students who aren't quite as adept at public speaking.