Microphone work and the rest of public speaking can be different skills, especially if you learn public speaking in a way that doesn’t involve a mic. Speaking wants you to keep your head scanning the crowd with your body centered when standing still. If your hands are free it’s good to use them for emphasis, and you’ll want to rest them when not. Standing still in front of a mic feels awkward. This results in decent mic work making you look and feel a bit like a stand up comic. At least that’s my experience with it from doing stand up. Mic work was definitely not the hardest part, but it was a constant balance when learning to keep speaking into the mic without coming off wooden or awkward. It’s also just awkward to hold something in front of your mouth while speaking.