For some reason, I fail to understand some of the points put forth by some folks. I see a real sense of entitlement that is not deserved. If you really want to fly in FC buy *&%$ seat in FC. That is what one friends does (well his company). My director flies so much that he refuses to fly in coach and as a state employee can not buy a FC seat. So he either pays the necessary coach fare to get an immediate upgrade via status or ponies up the miles when necessary.
Personally I think the pay a little more for the ticket with a chance of upgrading is a dumb game. I played it once not quite by choice. Do not need to do that again - i.e waste money. That said I do not mind the at gate calls that there are open FC seats and if you wish to upgrade it will be $XX.
Oh yeah and if a seat in FC flies empty maybe that is a way for the airlines to say - if you want it pay for it. But we ain't giving it away for free anymore.