The thing was so ridiculously expensive, I really doubt that was even a concern. They could have just made the 'spinner' unit a little bigger to fit those electronics; and the base a little smaller. I honestly cannot think of any reason that the product, as delivered, is built that way; short of planned uses that were never implemented.
The fact that, no matter what kind of custom cable you try to rig, it is completely useless without the base is just a staggeringly bad design. Other companies learned that lesson (IBM with the PS/1 that had the power supply in the monitor, or the even goofier Coleco Adam, which had the power supply in the printer of all places!) But Apple did it anyway. At least Apple only did it on a peripheral.