The British can just not comprehend the need for a united Europe in the modern world, where European countries are beset on all sides by many times more powerful rivals (Russia, China and now even the US is turning against us). To think that the little nation-states of Europe can survive and prosper on their own like they did back in the days of Napoleon and Queen Victoria ignores reality for the warm fuzzy feeling of epic fantasy.
The EU's goal is to promote peace an the well-being of its people (Treaty of the European Union, article 3, par. 1). The British either ignore this, or, if they know it, they don't believe it. Therefore, the public conversation about the EU revolves either around irrelevancies, like bendy bananas and fast-track airport lanes, or around issues that most people cannot really connnect with, like the benefits to industry (as if there is anyone left in the UK who believes that what is good for industry is good for everyone).
No wonder the Leave side carried the referendum vote. Their message was simple and to the point: "us versus them" (all of them - the EU, those krauts and frogs and those PIGS countires, Poles, Romanians... everyone). You cannot argue against nationalistic slogans and battle buses with "Brexit is bad for business". Nor with "I want my kids to be able to travel to the EU cheaply and without a visa". A powerful message is needed and it needs to make it clear to everyone what awaits us if we divide up and withdraw each in our little borders.
But, nobody has done that for the British- so, it's all identity, bendy bananas and travel privileges.