I suppose that complexity involves international ties, and some voters realise that their jobs are dependent on internationalism, so they don’t want to vote for right-wing isolationism. But some people are happy to vote for isolationism anyway, because they want to reduce immigration in many cases. Who knows what the future holds, but I guess we now have four years of Trump leading the free world to find out.
With a mathematically representative EU parliament then France and Germany shouldn’t be able to control anything by themselves because like you say, their combined population is less than half of the EU