To pique interest in something, you need to entice people with something appealing. What's appealing in the seasonal rankings? Only the top 1?!
Create:
1) A permanent tournament ONLY for the top 10 (???) --> followed by (possibly) a battle between the winners of these seasonal tournaments, like in "King of the Hill" (winner of Spring 2012 VS Summer 2012 - then the winner from that pair plays against the next winner of the Top 10 Autumn 2012 tournament... if they win, they become a two-time winner...).
2) Top 1-2 (???) in the Fortress Battles without selection (???) or better in the quarter-finals (or semi-finals of the Fortress Battles selection ??? - so as not to let them get complacent).
3) ... who else has any suggestions?
There was already such a tournament between the winners of the seasons, with your participation, which you, by the way, ignored :D :D :D
But to the point:
What's the point of fighting for the top places in the ranking if one player can afford one fun game a week, and another can afford 5, not even taking into account the strength of the opponents? Right now, it's just about the numbers. For example, I don't have much time for fun games right now - only tournaments. Moreover, there's no such competitive spirit in fun games as there is in tournaments.
...I don't think I need to say anything more about the value of the ranking, that it doesn't show anything...