Without this value, the state can continue to erect legislation in the name of "safety", or any other perceived inequity in society, until you can no longer move.
How perverse that English law used to be a bastion of civil liberty protections. Here's a great scene from A Man For All Seasons that shows what I mean: https://www.youtube.com/watch?v=PDBiLT3LASk
The UK however, maybe. Brexit was a real dumb idea.
What in the world are you talking about? The US has all of this internally. If on the one narrow point you want to claim that EU has open-borders to the rest of the world, no you don't and that's not something that's good to have anyways. Both US and European citizens are fighting their own governments to decrease immigration as polling shows large opposition to current immigration levels for many years now. A big part of the crackdown on speech in the UK is to restrict criticism of immigration policy.
A better example would be Americans being able to travel freely to USMCA countries.