I don't see what's wrong with the option to do that, if someone wants to have a dubious colour combination then so be it, but I agree it doesn't look great.
I don't mind the dark icons without colour tints, but they need to do them uniformly, such as on mine the Apple Store icon is bright white background while the others are black. Same as the App Store being shaded blue background. Also the Support icon.
The all the third party app developers have to get on board with the dark icon alternatives - and it's for sure some of them will not be pleased because it may well go against their own brand guidelines.