Here's why: Pop can be shameless. It can be absurd. Even dumb. Consider the song itself — my favorite lyric is, "she's got dumps like a truck" — and think about what kind of video we'd get today for it. Probably something NSFW. Yawn. (Although, it'd be amazing to see Eric Wareheim do something for this song)
NSFW wasn't an option in 1999, so you couldn't take the easy way out. But you also couldn't just ignore the song and make something generic. So, Kahn and crew created something that's impossible not to notice. It's clearly a booty video — proudly a booty video — but that also mocks man's fascination with the backside. It's over the top, but it's also lighthearted, comical and dare I say charming?