Many proposals have opt-out clauses, and a member can leave whenever it so wishes (which they can't, because it'd be economical suicide and foreign policy suicide, as well as losing a large proportion of the electorate's support).
There's also several key differences between what I'm suggesting, and what your example is. After all, the European nations are all much closer on a social, economical and political sense than the US and Cuba, and one EU members population doesn't dwarf the rest.
What I'm trying to say here is that the views from someone in France is similar to that as someone in the UK, which is similar to someone in Germany. There will be differences, of course, but those differences are no where near as big as the differences in views between someone in the US and someone from Cuba.
What's more, it's more democratic than what is really happening. Where the rest of the EU states have ignored RoI's "no" vote and are ratifying everything they can now, and are waiting for RoI to just "change it's mind".







