I feel like it was a real missed opportunity for Apple to leave the exterior of the Mini unchanged. This form factor used to have both a 2.5" hard drive _and_ an optical drive in it, and with the miniaturization of parts since then, as well as the reduced need for cooling, it could certainly have gotten smaller. (9 to 5 Mac reports a "30% – 40%" reduction in motherboard size.)
If retaining compatibility with certain mounting accessories was a concern, they could even have simply reduced the height of the unit, and I think it would have been an improvement.
If retaining compatibility with certain mounting accessories was a concern, they could even have simply reduced the height of the unit, and I think it would have been an improvement.