Americans have an unhealthy desire to see average people promoted to positions of great authority. No one wants an average neurosurgeon or even an average carpenter, but when it comes time to vest a man or woman with more power and responsibility than any person has held in human history, Americans say they want a regular guy, someone just like themselves. President Bush kept his edge on the "Who would you like to have a beer with?" poll question in 2004, and won reelection.
This ilustrates one of the problems of the US presidential system: the one job is both head of state and head of government, and the former aspect (symbolic) is much easier to think about than the latter (administrative) in terms of a candidate’s suitability. You may well pick a national figurehead based on what they’re like as a person, but the trouble is that they also get their hands on the levers of executive power.
People in the UK sometimes wonder whether Charles will be as good a monarch as his mother. But just imagine for a moment how he’d fare as PM.