I have 3 major concerns with this subject:
1. It seems like only with basketball do people complain about young people going pro.
Why? I think it has to do with race and class. There's a bit of a patronizing middle class "we need to make the right choice for these kids because they can't make it on their own" attitude. Of course, there's no outcry about players going straight into baseball (white, all-american) from high school, or into tennis (upper class) or soccer (predominantly foreign).
2. The outcry from the league is utterly dishonest.
The league does not care one iota for the individual athletes in question. They care only about protecting themselves from bad gambles because NBA owners have shown no willpower or self-restraint when it comes to a)free agents, and b)project players. Ideally, a team makes a calculated risk when it either signs a big free agent or drafts something of an unknown quantity. The teams know this when they enter into contracts. If owners were smart, they'd look around the league at all the mistakes and learn to make smart choices. Instead, they lobby to unjustly bar 18 year olds from their league to save themselves from themselves. Gerald Green, as an 18 year old, was able to parlay his basketball abilities into several million dollars. The NBA knew about him and had scouted him. By all accounts, he was not much of a student Had he gone to college and demonstrated a lack of true NBA skill while also failing academically, would the NBA have cared then? No, he would have been on his own and the NBA wouldn't have taken a second look as he flunked out and went on his way. Let's just be honest and clear that the age limit in the NBA is about one thing: owners' money.
3. People really only seem to care when it's an athlete leaving early.
There are millions of people in the U.S. who face a constant uphill battle against ridiculous obstacles just to reach adulthood, let alone obtain a good job, let alone graduate from college, let alone graduate from high school. When faced with a lifetime of hopelessness and trauma, I applaud any individual making a choice to take a proactive step to get themselves a foothold in society. It would be one thing if the U.S. provided adequate services that truly allowed any citizen the chance to focus on education and eventually learning a useful trade (does need-based scholarship really mean much in the face of constant violence and possibly the need to provide income, at the age of 16, for your family?), but by and large individuals are left to fend for themselves. To watch people grow up in terrible poverty, then say "shame" for making what you think is a bad choice, is not rational. I think it ends up being selfish. Many people do not care (or would even applaud the nobility of such an act) if a child of poverty left school early to work a job to buy food for his family. Many of those same people cry foul when a player leaves school early to enter the NBA or even earlier to chase Euro dollars. Why do they care now? Because this affects the quality of the basketball they watch.