Why Brexit? Meddlesome regulations.
I expected something like Brexit would happen eventually. Perhaps not first with Britain. Once the Brussels Bureaucracy began to flood the EU countries with meddlesome and often silly regulations that ordinary citizens and businesses were expected to follow, it became inevitable. It escapes me how anyone can think that meddlesome regulations from a nascent administrative state without real lawmaking authority and electoral accountability would unite the confederated but still sovereign nations of the EU, rather than divide them. Perhaps some ideological bureaucrat might delude himself into believing that, but it doesn't work that way.
Just Google "silly EU regulations" to find many of them. Such things are intensely irritating to people. It is an accumulation of thousands of small irritations that combine to drive people to rebel. The entire Brussels Bureaucracy needs to be sent home to find real jobs.
I have discussed this with several British friends, who all seem to agree it is the regulations that drove Brexit. Nobody minded the lower barriers to trade, investment, and travel (except of Muslim immigrants that are trying to conquer Britain by infiltration).
Muslim immigrants shouting to native Britons, ""his is our country now. Get out!" https://www.youtube.com/watch?v=tlBsG1UJoLc
The EU Parliament is not a true lawmaking body that can make laws for citizens of EU countries that are lawfully enforceable. Neither is the Brussels Bureaucracy authorized to make laws or "regulations" for ordinary citizens. Unless national authorities yield to them in a surrender of sovereignty. People want to elect their lawmakers so they can turn them out at the next election.
The EU has been experimenting with various ways to bring their members together. The one kind of experiment that could work would be a European Constitution. But the one attempt at that was so incredibly incompetent that it is no wonder the voters of France and the Netherlands rejected it. Nothing but vague, aspirational political slogans. To get a model for a constitution that might work see http://constitution.org/reform/us/constitution-us-model.html Compare it to the proposed 2004 EU Constitution http://www.unizar.es/euroconstitucion/Treaties/Treaty_Const.htm and note the differences.
What really works to unite nations is an external enemy. It appears that Russia is trying to become that enemy. We will see if that survives Putin. Fortunately he can't live forever.
So where does Britain go from here? Union with the United States would make some sense. The UK would have to lose the monarchy, and if it loses Scotland that might follow. If it does lose Scotland then another kind of union might be in order, something more like my model. It would also need a written constitution. The present legacy of "constitutional" documents doesn't really do the job. Neither do the Canadian and Australian constitutions. The Australian is still an act of the British Parliament. There is still a movement in the UK to seek a written federal constitution, but it seems to be dominated by socialists.
See http://constitution.org/ech/eng_const_hist.htm and http://constitution.org/sech/sech_.htm