I think exceptionally good students should be allowed to skip grades. I have some reasons why I think so.
First of all, being able to do something you want to do and do at own your level may be very good for you. Therefore, I think studying in the upper grades stimulate students' motivation for academic endeavor.
Another reason is that grade-skipping doesn't need extra fees for tutors or separate programs. The desire of the student to study reduces the cost needed. It will be very helpful for poor families to reduce the costs of learning. I want to eliminate the students who can't go to college because of their expenses. In other words, I want a society where people who really want to go to college can go. However, grade-skipping has a disadvantage that causes mental stress to grade-skippers. In addition they may feel that they were underachievers. Although there are some disadvantages, there have been many grade-skippers who contribute to society such as Son Masayoshi and John Bardeen.
For these reasons, I think exceptionally good students should be allowed to skip grades.