I used Special:Contact to send a message to Wikia staff about this. and here is the response I got:
Here is what has happened: Our Ad department has sold a premium achievement, which is where we allow companies to sponsor an achievement (cutting down on the need to sell ads elsewhere on the site). Of course, in order to give that achievement to your visitors, achievements as a whole needed to be enabled. You can learn more about this specific campaign here: http://sims.wikia.com/wiki/User_blog:JoePlay/The_Sims_3:_Late_Night_has_Vampires._How_much_does_this_make_your_blood_rush%3F .
The facts out of the way, I can now tell you that we made a mistake here. We have been doing this with a few wikis but this was the first wiki that didn't have Achievements enabled (much less the first one that had said they didn't want it), so the policy on this matter was not clear. Our specific team would definitely had either let you know ahead of time or prevented the campaign altogether if we had known this was the wiki they wanted the campaign on.
So, that's what has happened. What will happen next? Unfortunately, the deal is done, we are under contract and we will honour that contract. The campaign ends November 21st and I have gotten permission from Ads and our Support manager to turn off Achievements at that time.
I certainly apologize that this has happened to your wiki and understand if you are upset. While it may not be a big comfort, at least know that we certainly learn from every mistake as a company and that we will take a very strong look at the matter with our Ads Team when we meet up next, hopefully preventing this 'surprise' for other wikis in the future.
Tim "daNASCAT" Quievryn
Wikia Community Support
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