I swear, people here are so s t u p i d.
Anyways, well one, you can get college credit if you're planning to major in that field, so it depends in your electives in your first year.
Two, people take it because it's an easy course, an easy AP exam (in comparison to the rest of the AP exams). That means, higher GPA. And the more APs in your transcript the better. Additionally, passing the AP exam is easy, so it's good if you want to earn title of an AP Scholar, National AP Scholar, etc..