The EU was a good idea at the start. A bunch of countries wanting to preserve peace and increase trade? Sure sign me up.
That's what it was at the start.
But now, with the open borders between countries, laws that supersedes state laws, talks about having an army and a desire to turn European countries into the United States of Europe, what is the advantage here?
You could have pacts and treaties to foster cooperation and trade. You could share intelligence and help each other out just like any other country in the world does it currently without something like the EU to manage it all.