It's always been this way, X79 also had quad channel where the mainstream platforms did not. Short answers:
From a practical standpoint - It is not needed on mainstream platforms. If you feel you need quad channel memory then you should probably move up to the enthusiast platform anyway.
From a business standpoint - If those are things you really want, you'll have to spend more money and go for an 2011-3 CPU and X99 motherboard.
Cause really what's the point in X99 when Z170 has all the same features and pricetags?