I'm a remainer Rusty and have my reasons for being so. Nevertheless your concerns are legitimate and worthy of scrutiny. The idea that it doesn't work economically is a good one. In all geographical areas of human population and endeavour people will migrate to the centres of strong economic activity; some for business - to buy & sell, others for good wages. It happens in the EU, where the movements come from the south and east, to the north-west. In the UK, the same economic migration is towards the big cities, then, irrevocably south-east to London. That is not a reason for disbanding the EU - otherwise we should also say break up the UK for the same reason. It is, however, a case for reform.
Social & cultural differences are - I believe- a signifier of great success for Europe. We don't build walls of segregation and point guns at those with social & cultural differences. We embrace them and try to understand them.
Above everything, however, it isn't trade for me. Lots of Leavers have spoken about being content with the EU As a trading block and it does make sense. No, the biggest and most important argument in favour of the EU, for me certainly, is the preservation of peace on the continent.
The C20th is a massive scar on humanity. 70+ million dead and hundreds of millions injured and displaced through war. If the EU were to do nothing more than prevent another catastrophic global conflict from starting in our continent, then it will have succeeded. Matters of trade, financial commonality, economic migration and shared foreign policy are matters for discussion and resolution, not disbandment.