The EU is a protectionist island in a global economy filled with large ambivalent actors. It's less evil, more like self-preservation, or an immune system. There has to be surface tension to retain mass, and there has to be barriers because that's it's raison d'etre.

I understand the game theory, but I think politically, it would be easy to spin this as the EU being a bully who punishes you if you don't play with them, and many voters would prefer to tell such a bully to bugger off than to play along (indeed, a lot of the Leave campaign was already about how Brussels bullies Brits into doing things they don't want).