There are two basic approaches that strike me when it comes to free-to-play monetization, as I see it. The first is a sense of contempt for players who aren’t paying, with everything being somehow stymied or lessened because you’re a mere free player and not a proper paying customer. The second is the inverse, that you should get stuff even as a free player but you could get a little more for just a bit of money, so why not just toss a buck or two this way if you want to?
Functionally the two of them are basically the same thing. Both of them have the same end results, after all, wherein you are given encouragement of varying stripes to pay money. But I find that the contempt side of things tends to make me less inclined to pay money on a game. Somehow, “pay X to remove inconvenience” bothers me more than “pay X to get bonus,” even if the net change is functionally identical. So what makes you most likely to spend money on a free-to-play MMO? Is it the difference in what you get for free or for the money? Overall attitude? Or just duration of expected play?