Lewis was not, and is not, very popular in the academy. I think there are three reasons.
First, he did not stick to his subject, which was medieval and Renaissance literature. He wrote highly successful children's books, theological works, and articles accessible to nonspecialists, and was an acclaimed broadcaster. All this allowed his critics to suggest that he was not a proper academic, because proper academics do not throw their nets so wide.
Second, he was good at everything he did (except perhaps some areas of philosophy: he was famously bested by Elizabeth Anscombe when he ventured onto her home ground). This was perhaps the most infuriating thing about him. The justification for academic superspecialization is that one cannot do more than one thing really well. But Lewis did. He was a better Renaissance scholar than those who criticized him, moaned about him in the Oxford cloisters, and blackballed him...
