I think most commenters are missing the primary focus of the author's rant. This is fair, because his letter is laden with subtext that is probably not obvious to people who aren't intimately familiar with the iPhone developer community. I believe that the primary thrust of his argument is not that he should be paid more, or that his apps can't stand on their merits, or that he is no longer in a position to play gatekeeper.
Rather, his primary complaints seem to be with the Apple-approved and required distribution mechanism for the iPhone, namely their App Store. The App Store severely limits how apps can be sold, promoted, and used. It does not allow for trial software, it does not allow for returns. There is no built-in help system or feedback mechanism. Ratings cannot be challenged. And the "top X apps" is segregated by "free" vs "pay" but not by different levels of pay. Therefore it is much easier to sell more copies of a $0.99 app and climb the charts, displacing potentially far better but more expensive apps that are naturally going to have fewer sales.
Hockenberry's letter seems aimed at encouraging or nudging in the direction of fixing many of these perceived App Store deficiencies. That is why it is addressed to Steve Jobs, and not to other developers. He isn't saying "stop selling your $0.99 apps," he's saying, give all app developers a fair playing field to encourage innovation and risk-taking.
Oh come *on* people. I wouldn't normally endeavor to explain a very old joke, but the number of people dissecting this post in all seriousness makes me fear for our youth.
The My freelance gig in front of a Mac trolls appear in virtually every discussion about Apple Computer. The troll claims to have witnessed taking 20 minutes to copy a 17 MB file from one folder to another and proceeds to question all Apple users as to their platform choice. It is a straight forward copy-and-paste from a weblog entry (http://www.kottke.org/98/11/my-mac-sucks) by Jason Kottke. It has also led to some very inspired and amusing parodies.