You cannot even begin to draw comparisons between baseball and basketball. The system works for baseball because if you choose to go college and have to stay there three years, it hardly even changes your ETA to the big leagues relative to being drafted and signed right out of high school. High school kids will go to rookie ball, short season A, low A, High A, double AA, maybe AAA, maybe skip it...and this takes YEARS. the kid that goes to college for three years gets drafted in june, and plays a few weeks at some A ball level, but by year two are generally in high A...and get to double AA soon thereafter (if they progress). In other words, you are just trading minor league years for college years...
with basketball, if you are a legit pro prospect, you can get drafted out of high school and make an NBA roster relatively quickly if you are a first round level talent. going to school for two or three years sure as hell changes your ETA to the league.