Have you people never shopped for a counter-balanced display mount before? They're not cheap. We use Humanscale ones at work, and they're something like $400 each, and meh quality to be honest. The price of the Apple one is certainly high, but assuming it's actually very good and figuring in the Apple-tax, I don't actually think it's unreasonable.
Or, do people really plan on putting a $5000 display on a crappy plastic stand?
I think the question here is, why is this not an optional stand you can buy or use the cheaper version that comes with the monitor, as most people just want a stand not a humanscale one.