Its very difficult to strike a balance between F2P and monthly fees. I prefer the F2P for the same reason as Ichigo. Its a pay as you play and I don't feel guilty about not playing in a busy month as I won't be wasting $15 or whatever. With an F2P there has to be some revenue from the game for it to be properly sustainable. I agree that it isn't fair when you invest time and someone invests a day and load of cash to jump past you but life's not fair
. There has to be an incentive to buy content to provide the revenue but that content should be free if someone puts the time in. How long it takes is the kicker but it has to be long enough to make a player seriously consider paying instead. At the end of the day you get what you pay for.
As DoF will be a full game with a one time purchase I am not too bothered about the DLC afterwards. Most games offer microtransactions/DLC and I haven't seen anything said yet that leads me to believe I will have invest further money just to be able to compete.
We don't yet know what influence points you will be able to buy and how much that will "influence" your advantage over others.