Ya know, if they really wanted to push people up in yield, maybe instead of giving away F seats to the ungrateful masses paying $200 for a 7-segment transcon, they should consider selling them for a price that is within reach.
In my ideal pricing, a non-stop transcon would go for $200-$500 in econ, depending on availability, and F would cost $800-1,000. I think at that price, they might actually be able to sell the seats, instead of offering them for $2,500 and giving them away. And it might change some of the entitlement mentality, as well!
And I realize that DL and others are moving away from it now, but I actually like the idea of earning upgrade points. Then it really makes it seem like a reward instead of an entitlement. But it's almost impossible to go back and make you "pay" for something that used to be given away for free - at least not without destroying what little bit of goodwill remains.