Well, we learn the other works because they are the masters of language. Shakespeare is the wordsmith of this world. Tolkien built his work on them, just like Shakespeare probably built his work on Homer. These authors are, after all, still widely read for a reason, and they are also called classics for a reason.
Shakespeare has coined many of the words...I disagree about many of your descriptions of Romeo and Juliet and the others, but they do not belong here.