Just because I haven't been on both sides of the coin, doesn't mean that I have to walk in your shoes to make a decision on what I believe is better.
My point is this; why make someone wait to upgrade when they are ready to do so?
Since the airlines are all about the $$, why would you want to wait to make more (if that is what you want to do) if you could do it in a lesser amount of time?
Senority works because you have accepted it. When enough people decide that they don't accept it anymore, it will change. Not saying that it will happen, but that is how it will happen.
I am on the outside looking in. I may change my mind when in your shoes many years down the road, but now, I just happen to have different views.