Has that changed in the current generation? On the XBox 360, you could physically stick any standard IDE drive in the drive bay, but the console wouldn't mount it unless it had a hidden file verifying that it was purchased from Microsoft, which charged well over market value.

IIRC they were also using a clever (sneaky) application of copyright law to enforce this. They used a few special sectors on the disk to store an image to which they hold the copyright. The Xbox checks to make sure the image is there in the right spot before it will use the drive. So you can't pass off another drive as valid without violating their copyright.

That was tried with early video game consoles, and did not succeed legally.

Console manufacturers have a different revenue model. They get money from games sold for their platform, this allows them to sell hardware with low margin or even at loss.

Is this not the idea behind the Mac App Store?

Not really, no. Most of Apple's money comes from hardware sales.

“Services”, as apple like to call the heading they report App Store revenue under, is largely the fastest growing thing at Apple. While historically it’s true Apple has made its money on high margin hardware, the future growth seems much, much more reliant on services. I wouldn’t be so quick to discount the increasing importance of service revenue such as the app stores to Apple.