"Shakespeare's characters used the language the way Shakespeare heard it."
Well, that's not exactly true. Of course, Shakespeare's language was a stylized and heightened version of the language he heard at the time, even if we're only talking about the most educated, more upper-class people. In every era, there have been playwrights who have attempted to write dialogue that sounds like colloquial speech, and others whose writing is stylized or heightened in some way. And of course, as others have pointed out, people don't sing dialogue to each other in real life, so it's rather odd for someone who loves musicals to dislike Shakespeare on that basis. But I guess KingSpeed thinks that's different and songs are different from dialogue.