Since modern life is becoming more and more complex nowadays, it's essentially true that young people should plan and organize themselves, in order to stay competitive to social environments. Specifically, they will always gain other than lose if they plan and organize more.
Firstly, people are borned with sloth. As a result, if young people don't plan and organize themselves, they just do whatever they want. That might be a serious problem because they're always choosing comfort. That is, they're not able to get out of their comfort zones. One direct effect might be slowing down their processes on learning and working. My friend Miso used to procrastinate because he had no specific goals and organizations. He found himself lost ambition and didn't care about his process. Not only him, that's a common phenomenon to procrastinators. In order to overcome procrastination, he set up a daily schedule in order to remind what he needs to do, and attached full attention to it. Now he became less procrastinated than before because he found everything isn't as difficult as he thought when overcomed. 
Besides, young people may set unrealistic goals without plans and organizations. Idealistic is a term used to describe when people only care about what they want and ignored their personal factors. What may happen is they just trying to reach but never successes. At first people are ambitious and