This Hokage hosh bosh is just another trivial fact of the Narutoverse.

There have not been any set laws which tell who will become the leader and under what capacity. Hell, if Naruto does become Hokage, then it is simply because of the fact that he is extremely powerful and follows his guts, otherwise Neji or Shikamaru seem to be a much better choice.

When the 4th become Hokage, it was most likely because he was indeed the strongest in the village. He certainly did not have the amount of experience of leadership as Jiraya, Tsunade, or the 3rd. Also, Konoha seemed to be in the midst of or just came out of "The 3rd Secret World War." By putting the 4th as the leader, other countries would feel intimidated approaching Konoha.

Abdula was indeed correct by saying "they made Gaara the kazekage solely because that allowed them to monitor him and control and limit his activities." However, it would be more logical to make Gaara Kazekage because he is the most badass ninja in the village, which would make other countries have second thoughts on invading. The Sand was already weakened by loosing their former Kazekage (Gaara's father) and sending troops for the Konoha invasion (the sand trio's teacher said this somewhere), and putting Gaara as the head would allow the Sand to be protected while monitoring their most dangerous asset.

In essence, any bloke who is super powerful and has his/her heart in the right place can be come the kage of the village. At least for Konoha, Tsunade put it the best by saying "No matter what what crisis may befall on the village, the duty of protecting and raising the little leaves falls on me." (chap 238, pg 13)