I'd like to offer a counterpoint to the author's suggestion that "you'd be an idiot not to buy [and dispose of] a new laptop every year." I'm a software engineer and put a lot on my computer's shoulders, running an entire cluster's worth of software as part of my development environment. I value longevity and durability in products I buy. It's nice to pick a machine and stick with it. It's a long-term companion. It's…
That combined with resale make this kit very attractive to their customer base who can instantly choose to be in your camp or the author's camp.
On the other hand, the market probably doesn't value modifications or add-ons as well, so re-selling my year-old MBP with optical replaced by SSD, 750GB 7200RPM rust platter, and 8GB RAM would probably not be "cost effective".