I don't mean it in the sense of 'why our character, why not someone else'. I mean what reason is there for Akatosh to stop with us; what reason is there to no longer create dragonborn. Which leads to the next question...
Well, that was what i originally thought. But it doesn't seem to be the case. Because why was Reman Cyrodiil born with the soul of a Dragon? Why was Tiber Septim? There was no Alduin to stop in their time.