That is a perfect example of why a wiki is a bad idea. While there is really not a whole lot of info there, the history that is there is really not for players. I might have to rewrite it as a basic overview based on the World Player Guide at some point.
Personally, I don't think a wiki is a bad idea
in general. But, then again, I am not the one who makes such decisions.
Now, I do agree that a fully open, unmoderated wiki would not work and would be unfeasible, and would cause problems. One that was more controlled and worked towards the goal of being both a useful tool and sales aid, would and could work very well.
An official Shadow World wiki would require, at the very least, a small team to maintain and post the official material (which would not be allowed to be edited by the general public), and a way to keep official separate from fan-generated content (like how the Cyradon wiki keeps official separate from unofficial).
An official wiki could also be used to drive sales. By having the official material in smaller chunks, spread over many pages, that makes it a great short-term reference tool, and also makes it a perfect vehicle for driving sales of products that consolidate this information in more manageable formats (such as the Player Guides being produced for GCP) through the placing of links to those products in the official articles.
As for issues between GM and player information, you could easily create GM and player sections. This is no different than doing GM and Player sections in a book. There is nothing that keeps the player from peeking at the GM info in the book.
At least, that is my opinion on this idea.