The last thing we need is another "trainee president". Everything looks easy to a person who has never tried it. The closest experience to leading the country is being a successful governor of a major state.
What does Governor have to do with foreign policy or military command, which are the only real duties of a Presider? Otherwise the Presider just signs bills, or vetoes them once in a long while. He or she may from time to time send over a state of the Union.