If you are going to argue that people like this need to use more discipline, then you are going to need to base your argument on the idea that children today lack discipline. Presumably, you will need to identify ways in which you think children's behavior shows a lack of discipline.
Perhaps the most obvious thing to argue is that children do not exhibit enough respect for authority in today's society. You could argue that parents and school officials who do not discipline children are teaching them that it is not necessary to obey authority figures.
Another thing that you could argue is that a lack of discipline creates children who are too lazy and not conscientious enough to work hard and get ahead. You could argue that the problems of American schools are caused by students who simply don't care enough to be diligent. You could argue that this problem is caused by parents and school officials who tolerate slacking and do not require children to work hard.