Why isn't the popular vote weighted more heavily in U.S. elections?

We aren't supposed to be a democracy. The framers of the Constitution were Against full democracy. They felt that the lowest common denominator of society(read as "stupid people") couldn't be trusted to make informed choices with their vote. Therefore they made a Republic = a representative democracy. They also included several rules to try and make sure only Learned and Non-poor individuals could vote (ie. Male Landowners).