The No Numbers Concept
The fact that a traditional RPG is essentially a numerical simulation has spawned a number of very annoying trends in player behavior. Most of these types of behavior can be subsumed under the term "numbercrunching." Also called "min/maxing," numbercrunching largely involves the study of the game’s numerical systems and figuring out how to use it to the player’s best advantage. Therefore, becoming a better fighter is more a matter of allocating your points appropriately, instead of logical considerations like developing advanced tactics, using terrain effectively, and personal bravery. The player character is reduced to little more than a spreadsheet, and players become obsessed with watching their numbers increase. Unfortunately, the game system eventually evolves to accomodate this sort of player with provisos like high-xp farming areas, repeatable activites to raise use-based skills efficiently with a macro, etc.
It is my firm belief that the axiom "most players are self-centered bastards who will ruin other players’ experience at the drop of a hat" is greatly exacerbated by this numerical obsession. Why do players steal kills from other players? Because doing so will help their numbers increase. Why do players exploit bugs to kill monsters (or players) with relative ease? Because doing so will increase their numbers. Why do players use cheats and plugins that give them unfair advantages in the game world? You get the picture. Sure, some of this activity stems from a desire to simply ruin the game for other players, and some people gain enjoyment from this, but there is no way to deal effectively with this sort of player except to quickly identify and remove him from your game.
Now consider the effects of a use-based skill system where the numbers are effectively hidden from the player. This means he cannot see his exact strength or hit points, he does not know that his sword does X amount of damage per hit, and wounds are represented graphically only, either status bars, hit location indicators, or ideally an actual change in texmaps reflecting damage to specific body parts. The player will have a pretty good idea that he is decent with an axe, a novice at archery, and completely unskilled at alchemy, but he doesn’t have a number to refer to as his "skill." Once in a while, he may receive a system message telling him that he has learned something new about pottery, but these messages should be unreliable and ambiguous. He may even be able to compete for titles in various contests of skill, but this is only an indicator of prowess, not a measurable figure that you can watch increase as you fight your eight millionth orc. Sure, there are players who will still go camp the goblins for "skill," but he can’t really be sure it’s doing him all that much good, and if the designer has been building his system holistically, it’s not.
What happens now is that with visible numbers unavailable for scorekeeping purposes, plyers become less interested in keeping score. This puts more pressure on the developer to make sure there is plenty of interesting stuff to do for the player, once the possibility of spreadsheet tweaking is removed. Such a system requres more diligence and work on the part of the developer, in many ways, but the payoff is immense. With numbers removed, your environment becomes more immersive. With spreadsheets removed, you remove a great source of annoying player behavior. And you may be able to reclaim some of that market that abandoned computer-based gaming for more logical paper systems.

Unfortunately, their is a difference between what people say they want and what they really want. People claim that they want to roleplay and interact with others, that they want an interesting crafting system, that they want individual skill to matter, but they really want the “I win!” button. Fundamentally, everyone wants to be special, and a game gives you the chance to play a character that is special. If skill is the deciding factor, however, then a few people will rise to the top and the rest will not be as good. Since nobody wants to be a supporting character, this will drive people away from the game. To be successful, the game must be able to be manipulated – and to do that you need to have access to the numbers. This is why WoW is so successfull – any one, regardless of their intellect or coordination can go to any number of websites and find a template for a successfull character, view maps showing which quests yield the fastest xp and quickly powerlevel themselves to the top, thus becoming the most powerfull guy in the world, just like everyone else.
If you were truly going to take away the numbers, you have to provide some other, easily manipuable method of keeping score so players can judge their success. City of Heroes has an ingenious system of Badges which begins to address this, but even then people are still obsessed with numbers.
Perhaps the bigger issue here is that we need to go back to the pre-Internet social model. Games or social groups were aimed at small groups of people with very specific interests. Now a game must be aimed at the widest possible audience. It would be refreshin to see a company make an active decision to aim at a smaller group and say “We are going to make money, but we are not looking to have the next great worldwide hit. We are going to make a game for the hardcore roleplayer and anyone who doesn’t like our game doesn’y have to buy it”
Or maybe somebody could talk Mu into writing his own persistant world. He could probably do it with the NWN 2 engine…
The problem is people crave structure, a way to show them along the path. In a game with the design you talk about here, many of the players would feel uncomfortable, and lost. They need that number system to make them feel as if they are doing something correctly.
Now, with this number system you claim that with it there is no skill, that everyone can “be the best” no matter what. This is simply not true, and WoW can be an example of this simply because of it’s endgame content. Yes, I know, it is very easy to reach level 80, but raiding is where skill comes in. If you have the skill to co-ordinate yourself with 25 other people in a boss fight that sometimes is difficult by itself. It took months for Algolon the Observer to be killed, and less than 1% of the WoW population has killed him. ie. It takes SERIOUS skill to down that boss.
Sure, eventually the numbers grow as the game comes out with better gear and blah blah blah but by that time new boss encounters are made. “hard modes” was one of the best additions to WoW, it let the truly skilled rise above the norm, using only their ability to play their character well and be completely aware of everything going on around them and simultaneously manipulating the mechanics of the boss battle around them.
City of Heroes used to hide a lot of the numbers from people, so that people couldn’t min/max that way.
The numbers were reversed engineered and 3rd party tools written to monitor logfiles to report them.
Eventually the numbers were put into the game and shown using the standard client.
People want numbers. They will get them, one way or another.