A USE is not desirable, and the EU does not have to follow that model. But a Union is desirable because it gives you more clout in the world. It may be a collective clout, but that is better than no clout at all.
The UK tries to have it both ways, an independent clout, and a collective clout with the EU. Though that approach might be good for our national pride, it is very expensive and wasteful.
We need to admit that we are no longer the Empire we were. We need to downsize as a country. That means stopping punching above our weight, and stopping pretending we are a world power. That leads to a choice, do we become a small island that is inward looking and not contribute or do we join and try to lead a collection of states, and maintain our influence at a fraction of the cost?