Checked my LR catalog. Out of 12k photos taken on Canon DSLRs
22% ISO 100
18% ISO 125-320
60% ISO 400-25600
I primarily photograph events in the worst indoor flash-free venues imaginable, family pj-ish stuff, birds, aircraft and occasionally outdoor sports & macro. Base ISO DR may be an important overall performance metric but high ISO handling would seem to have more relevance to the average dad with a fancy camera demographic I fall into.
It doesn't seem like Canon is skimping on high-ISO performance for product differentiation, or to save a lot of money. The 1DxII is only a little better than the 6D2.
What some seem to be missing is that low DR prevents a superior way of getting higher ISO exposure indices (real-exposure "ISO" vs "ISO setting"). Imagine you are shooting someone sitting in a dark area and there are neon beer lights in the background, much brighter than the subject. The "correct" ISO for the subject is 1600 for the Av and Tv values you want to use (the real substance of exposure), so you set the camera to ISO 1600 (or auto-ISO does it for you), and the neon signs get blown out and lose their color. If you used ISO 100, though, and "under-exposed" by 4 stops, the colors of the lights could still be there, and you could render the RAW conversion to keep the color of the lights. On a camera with very high base-ISO DR, there would be little extra noise as a result. With a 6D2 and most older Canons, there is a much larger noise penalty from doing ISO 1600 exposure from the ISO 100 setting.
... and I can hold onto my legacy 6D, because the 6D2 doesn't offer two of the most important improvements I would hope for; crop mode 4k, and improved base-ISO DR.