I've felt for awhile now that subscription-based models often alienate people who are interested in trying the game but wary of paying monthly, while trapping people who are playing the game by making them feel like they need to get their money's worth, and then that they need to keep paying, lest they fall behind. I've always felt that subscription-based models should center their fees around time actively spent playing the game, so that when you log off, the timer stops, and when you're online, even if just afk, the timer ticks down. Or that the subscription should be paid on a daily basis, not monthly. Or both. A daily, time/$ system would be the way to go for subscription.
Upfront-then-completely-free business models have the stigma of paying upfront at all. How about play for free for a certain amount of days (a week? A month?) with--and this is the important part--no restrictions on content other than the arbitrary time period before you have to pay and possibly your ability to give items to others (but not necessarily to receive them) then, charge the player, and if they have decided they want to keep playing, they pay, and continue on for free? Simple, gives the game exposure and enough time for the consumer to pass judgment. See, if a game has an upfront cost and sucks early on, then the player feels they got robbed. The appeal of free-to-play games is that you get to sample the game to satisfactory length before deciding if it's worth being one of your various money sinks. Upfront models reek of wanting to be free-to-play but being afraid to let go of subscription models due to the stigma associated with F2P that this article pointed out ("If it's free, it can't be good"). They also lack the potential revenue of subscription OR free-to-play games because they half-ass their approach by abandoning both. Lower revenue = higher chance of content issues.
Free-to-play games are incredibly successful from a business standpoint, and depending on how they sustain themselves, can be successful from the playerbase's standpoint. The MOST important thing to consider is that the microtransactions remain as unintrusive to the core game as possible. Convenience in moderation and aesthetics are some of the best ways to do this. What makes free-to-play games shine where subscription can go wrong is that they take into account that not everyone has the same income. Subscription and upfront games set everyone equally, much like sales tax, where as free-to-play games allow richer players to pick up the financial slack of poorer or hesitant-to-pay players. Free-to-play also has the advantage that even someone who does not wish to invest a lot of money in a game may eventually cave in and buy something, while someone who has nothing but money to burn on such a pastime can do just that. The things available should always make the player feel like they WANT to buy them but could also live without them, not like they HAVE to. It is also important that there should always be things that people are tempted to buy, not enough that they feel manipulated by the offer, but enough that there's always the possibility of that moment where they go "Hmm, I kinda feel like spoiling myself today." If you play a F2P and eventually quit it, but feel like you did not regret spending any amount of money on that game (even if you're just lamenting on the amount you spent), then THAT is a successful F2P system. "It took my money, but I never thought it wasn't worth it."
A game like Trickster Online fails at F2P. A game like Mabinogi (in spite of all the whining) or Vindictus actually succeeds at it.
Edit: To add on, subscription and upfront models have the advantage that everyone is equal, because everyone is paying. Upfront, however, unlike subscription, sets everyone equal at the moment of payment. Subscription only sets people to equal as long as people KEEP paying. F2P has the hurdle that people should be rewarded for paying more but that the perks are arbitrary and not game-breaking.
Another thing people seem concerned about are douchebags. There seems to be some misconception that douchebags don't pay for games. This is untrue. There's an equal ratio of them in every game, regardless of business model Who's the bigger douchebag? The one who feels entitled because they have money, or the one who plays a game for free? They're still going to be douchey to you. At least with the free ones, they don't feel like they've paid for the right to be douches.
But really, I find this whole US aversion to the F2P model up until this point to be very much akin to our aversion to the metric system. And we're still avoiding THAT for some reason.
