Randy Kennedy had a short piece in yesterday's New York Times on the issue of museum admission fees. He quotes Philippe de Montebello as asking: "Philosophically, what is it about a work of art that makes it mandatory that it should be available for nothing?"
It seems to me that anyone who really believes museums hold works as a "public trust" should favor free admission. As Paddy Johnson says in the Times piece, "I’ve never thought the public should be charged to see their own belongings." Fortunately, no one really believes the works are held in trust, or else it couldn't be the case that "deaccessioning is not a dirty word." It's just something people say when they want to express disapproval of a sale whose proceeds are not going towards buying more art.