Purely ceremonial? Like the ceremonial bleep that Lord Foul sent to deeply Christian countries? Sorry I don't think any President should have Carte Blanche, there are definitely times when the answer should be no.
A more strict interpretation and following of the Constitution denies
complete carte blanche to the president---
see Article II, Section 2, part two. It is only with the advice and consent of the Senate that the president can, among
others, appoint ambassadors.