Why would they shut it down? A fan-created wiki section would be a huge sell, as it means the players are inspired enough to put work into promoting the product. Free marketing!
If it is indeed free, then they should have no problem giving the official nod for such a project. This has been brought up many times on the forums, with NO NOD from Matrix. I can appreciate that they don't want to lend credibility to anything that they don't directly control - but as they say - nothing ventured, nothing gained. They aren't willing to venture ANYTHING so far.
What Matrix Games SHOULD do is like what Bioware did with Dragon Age 2, use the wikia site as a place to go for teasers. Not only are all special abilities detailed there, but they were added piecemeal, 3-6 months in advance, which kept their fan base salivating through day of release.
That model of dribbling out information leading up to the release has been followed by many a game company. I entirely agree that it's an effective way to market your product, and actually get feedback which may head off balance issues that aren't expected.
But this marketing technique has ONLY been done on the forums. There's precious little of this sort being done by Matrix.
Now the game itself (DA2) was a let-down in some ways, but I digress. The centralized place to go for information (outside of the in-game Galactopedia) got a lot of people to buy the product.
As for DA2, I entirely agree - it was technically pathetic. Good story, but this is BioWare - that's expected from them.
But that required that Bioware do some work to seed, check and update the site. I haven't seen any sign of any willingness on the part of Matrix to do something similar. Maybe they can't afford to. Maybe it's a legal issue with intellectual property rights. Or maybe they just can't be arsed.