I think the US chose to have a president act as a sort of a king with a term limit. Other countries saw that and adapted it when they moved away from their monarchies, either giving the president king-like powers or giving them just a ceremonial role as head of state.
What's funny is that in the UK and in many former British colonies, there's still a king, but it's mostly a ceremonial role these days. So, things have basically reversed. A modern king who's a head of state is basically a figurehead. A president who is the head of a country may have monarch-type powers.