Individual students often ask teachers not to include the law of rape on exams for fear that the material would cause them to perform less well. One teacher I know was recently asked by a student not to use the word “violate” in class—as in “Does this conduct violate the law?”—because the word was triggering. Some students have even suggested that rape law should not be taught because of its potential to cause distress. (from the article).
My law school did teach law on CSC /rape. We were taught the Michigan statutory version and the common law version. The prof did give a brief "trigger warning" as follows: "I know this is a distressting subject, and I'm sorry, but I'm required to teach it. Besides, if you end up doing prosecution, or criminal defense, you will need to know this."
Criminal law - as the curriculum is currently taught in law schools - also covers a lot of things that might not be 100% necessary for the students (whether they end up practicing criminal law or not). For example, arson, and robbery (common law robbery, which is breaking into your house at night), among others. It also does not cover a lot of criminal topics which are heavily tested on the bar exam (fleeing and eluding comes immediately to mind).
But the same is true for so many other law school topics: They are taught on the outside chance the student will need to know them, but they are also taught because the way they are learned lead to important skills in law practice, whether or not the student uses that particular piece of law or not. (Like Corporations Law, and teaching "piercing the corporate veil." I am almost 90% certain I will never use that in my law practice.)
CSC, which in its statutory breakdown, has a lot of elements and things to remember, is useful for students to learn because they will have to analyze it in an exam question. And the steps that students use to analyze - comparing the bare elements they have memorized and applying them to the situation described in the exam -- are something they will do every day in law practice.