"...chafe at his insistence on setting uniform prices for their songs and videos on iTunes..."
because it ignores keen business insight by presenting it as another example of Jobs's mercurial nature.
Joel does a good job of explaining why this is important. It is about the way that the music industry uses pricing as a signal. And Jobs wants to own that signal:
"And Apple? Apple wants the signaling to come from what they promote on the front page of the iTunes Music Store. In the battle between Apple and the recording industry over who gets to manipulate what songs you buy, Apple (like movie theaters) is going to be in favor of fixed prices, while the recording industry is going to want variable prices."