Why aren't smart people elected?

Instead of relying on charisma, why not have Presidents based on intelligence and knowledge?  Someone who has a masters or professional degrees, has written papers and books, and is just a really knowledgeable guy?  Rather than, um, someone who's not.

presidents are now elected based on whether they've got skeletons in their closet.  anyone deviating from milquetoast cannot be elected.  Thanks to the press and hyper partisan politics our country (the US) is now a pile of shit.