Recently Sony announced an online brokerage system for exchanging real world cash with other players for in-game items and services. This is an interesting change from their previous stance against such practices. Obviously the monetary prospects outweighed their moral stance; typical Sony.
Long ago I used to find the idea of paying cash for in-game items or platinum to be asinine. After a few years I realized that games like Everquest, Dark Age of Camelot, World of Warcraft, and others like them are not primarily skill based. They are instead time based. The power of your character depends on how much time you have to spend on leveling up, earning money, and getting items. It has little to do with reflexes, intelligence, or skill.
This is in direct contrast to most games where the player's skill is the determining factor. Genres like first person shooters, fighting games, or shooters are purely based on the player's skill at the game. If someone happens to have superior reflexes or an inate ability at these kinds of games they are instantly competitive with someone who has spent a significant amount of time playing said game. Non-reflex games like strategy or simulations are similar in that they rely on the player's ability to reason or knowledge of the game.
Unfortunately the focus on time spent means a casual player is automatically at a disadvantage as compared to a hardcore player. They won't level as quickly, won't have the resources to get the same gear, and won't have the stockpiles of money that someone with copious time would be able to earn. Regardless of how skilled the player is with their class, after three months' time the casual player will not be able to compete on an even footing with a serious player.
In my opinion this is why the real world cash for in-game cash, items, and services market has thrived. Looking at a popular game auction site it appears that 100,000 platinum in EverQuest is currently worth around $50. If a person in the real world earns $25 per hour, with two to three hours of real life effort they've earned the equivalent of 100K in EverQuest.
Contrast that to how much time they would have to spend in-game to earn that 100K. Let's say they are a level 65 necromancer. Necromancers are capable of earning money quite well on their own but I highly doubt they consistently earn 50K an hour. Maybe on rare occasions when they get a rare drop or a rare mob spawns, but its doubtful it is anywhere close to common. Or take for example a warrior. Now a warrior is almost totally dependent on other classes to be effective after level 35 or so. Unless they get good drops while raiding it is almost impossible for a warrior to average 50K per hour. In fact I would guess it probably would take a warrior more like 10 to 30 hours to earn 50K.
It seems obvious that it is far more efficient, time-wise, to purchase platinum than to earn it in-game. At least for the time-constrained person with money it is. Since there isn't much skill involved in the game, what is the real impetus for not purchasing platinum? Is it cheating to purchase platinum? Does it ruin the game? That really has to be decided on a per person basis. I know that I have played a rogue in EverQuest for over six years. In that time I've earned hundreds of thousands of platinum. I'm a very casual player who doesn't belong to a guild. I'm perfectly capable of taking my rogue out and earning 100K platinum. Unfortunately it would take an inordinate amount of time to do so. I work full-time, have a house to take care of, and many other responsibilities. Spending $50 for 100K platinum seems very cost-effective compared to the hours it would take me in-game. In particular it seems efficient because the things that earn my character the most platinum don't do anything to gain my character skill or experience. Primarily it consists of killing particular monsters far below my character's level
By contrast in EverQuest 2 or World of Warcraft I don't yet have an inefficient high level character. In those games my characters are perfectly capable of earning a decent amount of money over the course of normal questing. I assume that like EverQuest once a player reaches the higher levels it becomes less efficient as the money made doesn't scale to the items available. However, I can't comment on it since I haven't yet reached that point.