A common cry among TV Tropes traditionalists is "We Are Not Wikipedia!" This invokes a Slippery Slope Fallacy that implies that any change to the wiki will lead to TV Tropes losing its "character" and becoming Serious Business. Of course, Wikipedia has a different mission in mind, so such a comparison is moot. Besides, when was the last time you heard a Wikipedian claim "We Are Not TV Tropes"?note Lesser used, typically as a response, is "We Are Not 4chan!", implying a descent into chaotic snarkiness.
A subset of Godwin's Law, and just like that one, invoking this law means the person in question automatically loses the discussion.
For the record, it is fine to disagree with the site's editorial or administrative policies. However, invoking blanket arguments such as "ruining the wiki" renders your opinion uselessly vague. It should go without saying that different people have different ideas about what makes the wiki fun and useful. Be specific and argue constructively.