To me, the idea that approval from colonies is no longer important makes sense.
What are your colonies going to do, if they don't like their Core World which they're tied to? They're basically slaves, meant to work for their Core World. If they don't like it, too bad.
I accept that Stardock need to remove all discussion of "Colony Approval" if that's the case - Colonists are just slaves, so who cares if they don't like the atmosphere on ZiggyLoveXI?!
If that's the way Stardock are going, I'd suggest that if Governments are coming back - and they most certainly should - then it's only the Core Worlds who get to vote. That's yet another step on the road to lessening the micromanaging of your empire.