I also think it interesting that you use Shrek as an example of a silly Broadway musical. Of course, Shrek and Caroline, or Change were composed by the same woman- Jeanine Tesori. I'm guessing you haven't actually seen Shrek, or else maybe this just slipped your mind? But I'd suggest that Shrek the musical is potentially more complex than you might suspect.

You write that independant theatre, unlike Broadway (which fulfills an obliquely "different role"), leaves one "transported and transformed." Independant theatre provides "a revelation" and lets us "know that something is happening right here, in the same room, that we are both witness to and participant in."

This is an extremely simplistic division- "independent" theatre does this (occasionally), but commerical Broadway does it as well. Both types of theatre can be as intellectually and emotionally stimulating as they can be midn-numbingly dull. But you wouldn't know this, because you write that you rarely see Broadway theatre.

If you choose to write off Broadway as commerical and populist and unintellectual, that is your choice- I'd just ask that you learn a little bit about it first.