They are now. They wouldn't be if defensive rate didn't impact your ability to climb.
Maybe I'm just jaded from previous games I've worked on, but I've seen what it means when participation trumps all, and defensive losses mean little/nothing. That isn't to say that defensive win rate is perhaps too important in our current system, or the fact that the current system de-emphasizes participation too much, but that I think the inevitable conclusion of ensuring participation is rewarded above all is a dangerous direction to follow to it's logical conclusion.