One of the common complaints against the subscription model is that if you only play that MMO sparingly (whatever that may be for you), you are not really getting your moneys worth compared to those who play more. The perceived plus for a F2P MMO is that you (ideally) only pay for what you want, be it content or fluff, and you control how much you spend based on how much you play/invest in that game.
While the above is true, I never see people talk about what happens when you really like a F2P game, enough that it becomes your main or even only MMO. Assuming a F2P MMO is of that quality, now you are no longer the casual jumping in from time to time, but the hardcore player logging in often and experiencing more/most of the game. When that happens, you will wish your new favorite MMO was a subscription game, as you will be paying FAR more for the F2P MMO monthly than you would for a subscription.
That after all is the F2P model, those who play for free/little are supported by those who play and pay far above the average. I believe the reason more people are not up in arms over having to pay MORE per month to play a quality MMO is that simply put, most F2P MMOs are at best average, games that might do a few things well or unique while the rest of the content is cut/paste stuff you have seen 100 times before, usually done better. In other words, if WoW used the traditional F2P model (and each patch brings it a little closer), a lot of people would be paying out the nose to play it because WoW is the main/only MMO for so many. On the other side of the coin, my guess is most adults playing Free Realms do so with their kids, or jump in to take a look before move back to a ‘real’ MMO. The issue facing FR is that if it was a sub game, I doubt SOE would be putting our press releases announcing that 18 billion people have glanced at an image related to their game since its release, and so a sub model is not much of an option.
Aside from being little more than a money trap for the hardcore, the F2P model also influences game design. Tobold has a post talking about his reason for leaving Luminary, a game he originally enjoyed due to its unique selling points but later found those same selling points as negatives due to F2P business model influence. His experience mirrors my experience with Atlantica Online, a game I ultimately wished was a subscription game and not F2P. Just like Luminary, what I initially found appealing in AO was later a negative not due to design, but due to the business model.
This ultimately is, IMO, the major crutch of the F2P model, it only really ‘works’ for those who drop in and out, spending a few dollars on a quick purchase and move on. Those that don’t spend anything are just leeching bandwidth/space, and unless you become truly addicted (plenty of those stories from the East btw, Google is your friend), a hardcore player will find more value in a subscription game than a F2P one, especially now when most (all?) AAA MMO titles are sub-based. It would take a truly exceptional MMO to pull the hardcore away from current AAA MMOs and into a F2P game that they will need to spend MORE per month to play, which is somewhat of a risky gamble on the part of the developer. By that logic, the ‘ideal’ F2P MMO is what we currently have; games just good enough to downloading and keeping on your desktop, but not anything that becomes the main/only focus of an MMO gamer. The true junk titles get deleted, and those that get near the AAA status go subscription (Aion for example).