I think the free movement of goods and services in Europe through the EU common market has been of great benefit to the European countries.
The problem is all of the political baggage. Norway and Switzerland have done very well there they are associate members so benefit from the common market, without all of the political baggage and this is what the UK should have done.
Some of the major problems Euro, Common Agricultural Policy, Common Fisheries Policy, Brussels (or Strasbourg to keep the French happy, where EU parliament switches to here twice a year - Total madness
) Incompatible legal systems. In UK everything is legal unless made illegal, In France everything is illegal unless there is a law to make it legal. The French influence means that all of the Common Market trading standards are micro managed. Socialist human rights and employment laws, which destroy jobs. Most EU countries have had much higher government spending than this country, high taxes, inflexible labour laws and high unemployment.
The UK used to be one of the exceptions to this and had much lower taxes and unemployment, but where Government spending has gone from 32% of GDP in early 1990's to 52% now. We now have very high taxes, much more restrictive employment legislation and a official unemployment rate of 8.1% and a real rate much higher than this.
Personally, I think anti-democratic Brussels is the EUSSR. At some point when the whole of Western Europe has become very, very poor compared to most of the rest of the world, then it will all fall apart, like the USSR did (this took 80 years). I just hope it happens peacefully.