The design makes sense as explained in the article. Taller and more antennas, perhaps those were issues that needed addressing based on the previous model consumer feedback and testing. It does have a smaller footprint and might look cool on your desk just like your Darth Vadar head coffee mug that holds all your pens and pencils.
This just confirms my thoughts as soon as I saw both new Airport and Time Capsule.
They redesigned the Time Capsule to make it smaller and re-using the ideas from the new Mac Pro, and then, in order to provide with an Airport, they just removed the hard-drive.
In the end, Apple is just saving a lot of money with the manufacturing process because it won't need two molds but rather one for the main case, and pretty much the same for everything else. Like any other company, they realized they have to optimize and converge into the same shapes for the devices.
It's unlikely though that an Airport will be usable for allocating the hard disk as said by iFixIt... it misses ports and probably controller chips but... I guess that the parts will be easier to sell and that's the reason for the high repairability given.