Okay, Glenn. This is what Suzanne Calvin at the Dallas Opera says about the musical/opera distinction:
Les Mis is an opera, by the usual rules. I suspect it’s always been called a musical simply as a marketing tool to sell more tickets, especially to folks who might be slightly intimidated by the very word “opera.” Opera neither bites, nor fatigues, nor does it taste bad. Opera is entertainment!”
Now, having said that: not every line in every opera is sung. (Look at Beethoven’s Fidelio or Mozart’s The Magic Flute, with spoken dialogue.) It has more to do with the perception of musical sophistication; however, Les Mis certainly isn’t lacking in the sophistication of either music or text, so, again, I’m betting that it’s simply a marketing decision.
