Seems logical; bulldozing through historic buildings is the responsibility of the World Heritage Centre so should be sanction free, but contemplating a tall building in the outskirts is a serious threat to integrity and the state party should be held accountable.
Dresden is general very well preserved and many countries (e.g., China) change much more of their WHSs with no threat of delisting. The Great Barrier Reef is not even on the In Danger list, mind you. I still lament the delisting of Dresden. I don"t think it ws justified or that it effectively contributed to preservation elsewhere.
I think there is an argument to be had that a rich country like Germany should be held to a higher standard than a poorer one, e.g. Uzbekistan. Still, it sounds pretty dramatic what was done and should have consequences.
Having been to Dresden last weekend, the complaint itself seems a bit far fetched. The bridge isn't even visible from the center. And another ugly concrete bridge dating back to the 60s (Carolabrücke, really ugly) runs right through town. In the end, I feel this was more about the process and communication than the merits.
On a more general note, a site like the Aachen cathedral wouldn't look like it does if the standards had been in place 200 years earlier. Sites change.