I agree with the above, with two caveats/clarifications:
1) Apple has more than its share of rabid fans, but it's not just the media that has insanely high expectations of them; their users howl about every real and perceived fault. I'm a long-time Mac user, and have caused many friends and family to purchase them too, but boy do I hate their mice, cloud services, and every laptop screen they've ever put out before the retina.
2) The market will bear what the market will bear. Going back to Apple, everyone said the iPad mini was overpriced, but they still couldn't keep them in stock. Lowering the initial price would have just been a bad business decision that would have left money on the table. $30 for a Lightning cable is a lot, but now there are cheaper options available. $1500 for this lens is a lot, and will either plummet in price if the naysayers here are right, or will stay high if it does turn out to be as popular as Canon bet on.
Ultimately, I hope the performance problems Photozone found are limited in nature, as supported by other reviews not mentioning the problem and other users who can't reproduce the problem. If not, then Canon truly made a misstep not only in the pricing, but in releasing a lens that simultaneously offers high-magnification performance as a headlining feature yet suffers from critical issues when using that feature.