Well, that is your opinion, and you have your right to it. In the realm of ideas and likes, no one person's opinion is right. I did not specifically address some of your points, as I see them as invalid.
Statistics support me, in this case. Would the game be be better if it had strict rules for mental and personality stats? In my opinion, -for me- yes, to a certain extent. It would also be a lot emptier, and nearly impossible to code. If strict rules were enforced, I would be staggeringly surprised to see more than five to twenty people online at a time. You may think that would be a good thing, but I do not. I enjoy the personalities created by other players, including their self assigned mental stats.
And that, Draklar, is how this Massively-MultiplayerORPG would fail. It would become a tabletop mimic MORPG, built around just those few that can play specific roles, and enjoy doing so in a virtual, computer-generated world. It would fade for the minds of most of the people who play it now, and become a small cult game.
Since we are on the subject of a better system, what do you propose to do, and how could the code be made to support it? I give you two example characters to base your system of enforced mental and personality stats on, three potential player types, and some potential situations. I left out my player type, as I could play either of these roles easily without any extra code.
One: This will be a young Dwarf of surpassing intelligence (high INT) He is a renaissance type, skilled and learned in many areas. He is an inventor and philosopher. People group around him when he starts to give a talk on one of the many subjects he is very proficiant in (high CHA). He even has some training in the art of battle and fighting, as his father was a trained soldier, and saw fit to pass his knowledge onto his son. The dwarf is not without flaws, though, as his pride often gets him into trouble with his fellows and foes alike (high WILL/Pride). He is also afraid of deep water and most animals, though for unknown reasons (low bravery). He has no problem at all switching to the highest bidder for his works, despite what may have been promised (low Loyalty, high Greed). He will never however, take something that does not belong to him.
Two: This is an elvish fisherman's daughter. She takes after her father's side of the family in the intelligence department, to her mother's great disappointment (low INT) She is often coarse in language, and prefers using her fists instead of her brain to get out of most situations. She is barely literate, and often has a hard time getting her point across to others (low CHA). She is fast to anger and gives up quickly when faced with a problem she can not easily solve (low WILL). She also tends to have sticky fingers, and does not respect other's possessions (low Honor), but even being a thief, she never sees fit to take more than she needs (low Greed). The one thing she shines in is sticking to her friends and defending them at any cost (high Loyalty/bravery),
The player types:
A: The friendly player who likes to help people. Let’s say he is not very smart.
B: Drey or Seperot, who I find enjoyable to play the game with, but find to be limited in roles they can play (from experience, anyways).
C: The very smart player who is not a very good RPer, and loves to finish everything.
The basic situations:
1: A very valuable purse or item is seen being dropped unnoticed by a fellow player or NPC.
2: There is a debate on advanced construction, which the Dwarf has the stats to know about, but the Elf does not. The same can not be said about the players.
3: The only way to get to the next quest is to cross deep water on a boat.
4: There is a very hard maze that needs to be solved.
5: You need to talk some folks (NPCs or players) into helping you do something (group quest, maybe?). More specifically, the elf has to talk the dwarf into doing something.
6: Other.
Now, in a PnP, every one of those situations are easy to control using nothing but the reasoning of the GM. Now, come up with a code solution strict enough to force all players to act out those situations correctly (as you see it), yet flexible enough to account for the infinite other situations that could arise. That is your test. Remember, the clock is ticking, and I grade hard.