And more to the point, why doesn't the whole of the UK have any vote in this potentially ruinous folly?
Just my opinion, mind...
The UK is set to have a vote on whether to stay in the EU or not, and you can imagine the reaction if it became known that the vote was to be extended to the entire EU (it would, after all, affect them also). Just imagine the situation if the UK voted to leave, but Germany, France, etc, said no, and we had to stay (doesn't sound too democratic).