What is the conductor for, exactly?

I'm reading "The Art of the Conductor" by John Watkins (2007, published by iUniverse). So far, I disagree with just about everything he's said.  This is his take on the conductor's role in interpreting music:-

"Only after [perfected baton technique] has been achieved can the conductor concentrate on the interpretive side of his job and reproduce, through instrument and voice, the effect that the composer had conceived in his mind and painstakingly drafted into a manuscript.

By the time an original music score has had its early readings, corrections, and rewrites, it can be considered to be finished.  The conscientious conductor will try to create a faithful reproduction using the composer's instructions for dynamics and expression.  It is unfortunate that some "pseudo-virtuoso" conductors consider their version of a piece superior to that of the composer's.  These conductors ride the composer's coattails and try to capture personal glory with extravagances of style and mannerism.  They are often praised by the undiscerning in the audience and by those who enjoy sensationalism.  In fact, these conductors are betraying the composer - they are using the composer's work to satisfy their own egos."

Ouch.  Those are strong words.  I think Mr Watkins has it totally wrong.  Here's why.

1.  A composition is never "finished"

Once a composer completes a composition and sends it out into the world, he sets it free. Okay, he still owns the copyright, but the composition becomes an independent creature, to be interpreted by many musicians (the composer hopes) in many different ways.  That's one of the great joys of live music - a piece is never the same twice.

In the case of music that's been around for a while, we rarely know what the composer intended.  Most of the early, renaissance and baroque music we perform has been edited multiple times.  Must a conductor slavishly adhere to an editor's intentions?

2.  Horses for courses

If I'm leading my choir in a large space with a two second echo, or at a function where there's background noise, or outside at a summer event, I'm going to conduct them differently.  That's not betraying the composer, and it has nothing to do with my ego.

3.  The audience is king

"They are often praised by the undiscerning in the audience and by those who enjoy sensationalism."  Grrr.  This really raises my hackles.  Accuse me of being "undiscerning" if you like, but I believe that good music is whatever you enjoy.  I love a wide range of musical genres, but I pretty much don't get jazz.  A lot of it sounds to me like an unstructured cacophony, but there are people who adore it.  Which of us is "undiscerning"?  If you think music is good, it is.

My job as a choral conductor is not to impart the composer's intentions to an audience (if a composer wants their intentions imparted, they can jolly well perform the piece themselves!).  No, my job is to lead my choir effectively so that we can convey the emotion of the music to the audience.  The audience is the recipient of the music.

Don't get me wrong.  I'm not suggesting that the composer's stated tempo or dynamics are immaterial, but I'm the one responsible for creating a performance from a specific group of singers in a specific venue on a specific day.  The composer had none of those variables in mind.  Whatever sound he had in mind when composing the piece will never exist in reality.

Ultimately, I suppose I see the creation of a musical performance as a collaboration between composer, conductor, musicians and audience.  That's what inspires me, and if that's "using the composer's work to satisfy my own ego", so be it.

What do you think about the conductor's role in the interpretation of music?  Do you disagree with me as vehemently as I disagree with Mr Watkins?