If you disagree that he should not be studied, then you must think he should be studied.  The main reason he should be studied is that there are so many references and allusions to Shakespeare throughout our literature and common culture, and an understanding of Shakespeare is key. 

One thing to argue is that you need to be exposed to Shakespeare for the purpose of cultural literacy.  If you are not familiar with the basic plots of a number of Shakespeare plays, you will look stupid when you can't understand people's allusions to Romeo and Juliet or to Hamlet.

In other words, you're supposed to argue that Shakespeare should be studied in school.

For one thing, you might say that if young people aren't introduced to Shakespeare in school they might never have another opportunity to be introduced to Shakespeare at all. Not everyone would consider this a great misfortune, but a certain percentage of people would really appreciate Shakespeare and get pleasure and enlightenment from reading his works and attending performances of his plays throughout their lives. Shakespeare really is a great writer. He not only writes beautiful poetry but he has a lot of practical wisdom to impart.

After all, Shakespeare is widely considered the greatest writer who has ever lived. A good school owes it to advanced students--at the high school or college level--at least to give them some exposure to this writer who has influenced many other writers throughout the world for centuries. If schools don't introduce students to subjects of this caliber, maybe schools themselves are not necessary. Are they only to exist for the purpose of teaching trades? Isn't culture important? Isn't life more than just workinig and eating and watching television? Shouldn't schools be trying to raise the tastes of their students?

Leaning Shakespeare doesn't have to be mandatory. It could be optional for students who are interested--and this might be better in the long run because there are some people who hate Shakespeare and do not benefit from reading his works.

Shakespeare seems difficult to the young person who encounters him for the first time, mainly because of vocabulary. But it must be the case that many young people who found Shakespeare difficult and boring eventually learned to appreciate him. Appreciation is one of the main purposes and benefits of academic instruction.

Reading and understanding Shakespeare requires a certain amount of mental effort, but mental effort is something that schools should expect and require of students. Understanding Shakespeare is certainly not as difficult as learning French or Spanish or German or Latin--but learning foreign languages has always been a part of higher education. Schools shouln't be under pressure to make things easy and enjoyable. They have to prepare students for living successfully in a world which is not always so easy and enjoyable.

If Shakespeare were not difficult for novices to understand and appreciate, there would be no need to teach him in schools.