I was somewhat optimistic that in the Glorious Age Of Obama executive power would be used more responsibly, but I never for a second thought the administration would effectively cede any power. "We can do whatever we want" is the ultimate legal CYA and I'm not surprised that the people tasked with making such arguments make them. I did naively think that the Republicans might find their Impeachment II: Kenyan Muslim Boogaloo groove by going after such abuses, but that's pretty unlikely.
The executive is going to claim they can do whatever they want. The good guys we elect just might handle great power with great responsibility, but even that's pretty unlikely. And the bad guys we elect, well...