It appears to me that Canon is compromising by sacrificing properties that can be fixed by in-camera software, or in post processing for properties that cannot. They seem to be giving priority to center, corner and edge sharpness and to eliminating chromatic abberation. Distortion at the wide end or long end can be fixed by software, while sharpness and LOCA's cannot.
This formula might also be applicable to a new 24-105 mm lens, just because it is not in the examples does not mean it won't happen.
In any event, it is a very complex lens, moving three or four lens groups at a time and with extreme precision will mean tighter tolerances, and higher prices. Be ready for $$$$.
Simply constructed primes are looking better and better. I've nothing against zooms, but as mechanical complexity increases, so does the possibility of misalignment or malfunctions.