I agree with the sentiment, however in some ways it should be something that is permitted to move.

The UK has been very stable for a long time, however they are profiting indirectly from the museums, since it s a driver of tourism.

Should the UK become less stable, we should have a hard look at ensuring the continuity of the collection. As others have mentioned, a lot of these things would have been destroyed or forgotten had the British not decided it was important to keep it - and as time goes on, those things become even more irreplaceable.