Firstly influence, proportionally the UK is 17% of the EU's economy, 13% of the population and its most powerful military, the biggest break on the UK's influence within the EU is in fact our reluctance to use that influence, using that influence to shape the EU will give us more influence on the world stage (for good or bad) than we will ever have alone, Outside the EU we will most likely align ourselves more with the US, I have a feeling you would be unhappy with that.
Secondly social trends, the EU has its faults but in many ways it has acted as a brake on the actions of UK governments especially Tory ones, the European Courts in particular have prevented much, Outside the EU, I suspect the UK will tack more to the polictical right, reducing such things as employment rights (in the name of economic growth) especially given that a backlash against immigration was a major drive in the leave vote.
The idea that the EU is holding back a working class uprising is even dafter than the idea than the one they're stopping us from rebuilding an empire.
The economic arguments are many but the best one is the fact that our economy is so tightly intertwined with the EU, I will give you an example, someone at work was bragging to me that he had bought a Ford rather than a BMW because of Brexit, firstly the Ford Focus is built in Germany not the UK as he believes, there are no Ford car factories in the UK but there are 2 Ford factories which make parts that are shipped to Germany to be put into the cars. Trading under WTO rules doesn't just mean that UK charges tariffs on the complete cars coming here, it means that the Germans charge tariffs on the gearboxes going there from Dagenham, Ford have already announced they will review the fate of the Dagenham plant post Brexit, at some point it may very well decide it makes sense to just make the gearboxes in Germany as well, There are a LOT of UK businesses like that and it makes sense to move production from the smaller market to the larger one, a post-Brexit Labour government would be powerless to stop it and a post-Brexit Tory one wouldn't even try.