It's easy to say that now, we being adults long out of high school. Do you really expect a high schooler to understand that? I sure as hell didn't back then (my guidance counselor strongarmed me into a curriculum specifically around meeting UC and CSU requirements, despite me having nowhere near the GPA to get into any such school), and thus admission into a 4-year university was an extrinsic motivator that seemed unrealistic and was therefore ineffective.