So why continue to use a song that had quickly become shorthand for "No matter how low your expectations, get ready to lower them!" Well, Hollywood thinks you need to be told exactly what sort of movie you're going to be getting. When you need to communicate that the main character is a live wire, why use cliched dialogue when you can use a cliched Ton Loc song instead?
The voice of several generations, apparently.
If the comedy has a big enough budget, they might even go with the nuclear option: Smash Mouth. Hollywood loves the shit out of some Smash Mouth; presumably because their songs are genetically engineered to get stuck in your head like some sort of incurable mind-AIDS. Also, they all sound the same, so instead of using that "All-Star" song like Shrek (and Mystery Men, Inspector Gadget, Shrek 2 and Shrek 3), you can get the exact same effect by using one of their many other identical-sounding songs; like in Made of Honor, Can't Hardly Wait, the two shittier Dr. Suess Movies and the shittiest Austin Powers.
In fact, every comedy genre has a preset approved-for-trailer list that runs about two songs deep. Romantic comedies get The Cranberries "Dreams" or the Spencer Davis Group's "Gimme Some Lovin.'" Feel good comedies almost always use "Walking on Sunshine" or the most overused song in movie trailer history.
Yes, the only way to communicate that your film is the "feel good comedy of the summer" is to play James Brown's "I Feel Good." Apparently, Hollywood believes that you not only need to be trained like a Pavlovian dog to know what kind of movie to expect, you need the lyrics to literally tell you how to feel.