The EU is a noble but ultimately ill-fated theoretical experiment.  Peoples and nations cannot be expected or counted on to make every collective decision rationally and predictably to fit within a preconceived construct.  Their culture and history, which makes each of them unique, necessarily forms the contextual background in which they operate and against which they assess what is presented to them.

Thus, what the point heads in Brussels devise as an elegant, forward-thinking plan may not go down well at all in Normandy, Lancashire, Tuscany or wherever and, with a sufficient accumulation of such "doesn't fits" we see a Brexit like movement begin.