Again (don't know why you said again but ill add it too), if they cant read by junior year I doubt two more years of the same shit is going to help. Is illiteracy an issue? Sure. Should junior and senior year english be mandatory for every student because some of them struggle with reading? No, just make a class to help those kids.

Without a tailored class your just sticking kids who cant read well with more advanced kids in the same class and by senior year that gap has probably grown substantially. How do you make a single class that can challenge good English students and also nurture people struggling with the fundamentals? You don't. The high functioning kids are bored and unengaged and the struggling kids are stressed by how far behind they are, it doesn't help anyone.