It is a personal opinion - as stated at the bottom in my signature I don't represent EA or Envision and the views expressed are my own.
I'm baffled, what is illogical about the winners winning the rights to do things. Generally they do not stop all others, just those they won against. I know of no world where the fortress has been hit only once and ALL other alliances are prevented from hitting the fortress.
You obviously don't understand the concept of losing! You would be punishing them - what's the point of killing the fortress if you're being prevented from following that through with other control. What you'd get is an alliance controlling the centre, hitting the fortress for fun but not killing it so they aren't 'punished' by being forced to leave the centre. They'd just sit there.
They effectively do own the server, they won the server.