When you have the head of a federal law enforcement agency telling state and local governments that they will feel his wrath, we are ever closer to no longer being "the home of the free". These state and local law enforcement and government officials need to be protected from federal overreach.
Furthermore, they are not obstructing ICE's mission, they merely are staying within their jurisdiction as state and local law enforcement and government officials. ICE has Federal jurisdiction while they have state and local jurisdiction.
This "do what I say or else!" way of governing is what this country was founded against. This administration is beating on the drum of "Law and Order" while simultaneously stepping on the Constitution. It makes no sense.