Wikipedia is all about trying to get a reputation as an authoritative source. To this end it enforces all sorts of rules, such as constraints about how "notable" a subject has to be to get an article, a demand that claims be backed up with secondary sources and so forth and so on. If a long-time Wikipedia editor decides to give All The Tropes a go, you can bet that they will bring some of the culture with them.
This can be a bad thing because it means that out of habit, or just for lack of knowing any better, they can get hung up on things that do not matter on this wiki and set its goals back. The big one being humorous language. They might quibble about taxonomy, take issue with "vague" and "imprecise" wording (which is just our writing style) or insist on pursuing a source for a claim that reasonably stands on its own. They will go beyond the reasonable effort to write in an objective tone all the way into writing dull, terse and detached prose.
Wikis are about people sharing what they know (or suspect) about a topic. Wikipedia is just one of them, with its own goals and culture, and with all due respect (and there is due respect), our goals are different and our culture is different.
On All The Tropes, There Is No Such Thing as Notability. If you say something we'll take your word for it and figure that if you're wrong, someone will come along and correct you. We're more about a fun, entertaining, pithy style than about dotting our is and crossing our ts.
If you came here from Wikipedia, capitalize on the editing practices you brought with you that are also good here and stay away from the ones that aren't, and you're bound to make yourself useful. To make this work we're going to need effort, input and inspiration from all across the Order Versus Chaos axis—so go ahead, trim some Thread Mode and cut on the Purple Prose. Go on, have fun!