I am not an extremely nationalistic guy, but I don't like the idea of merging so many different countries, so many different cultures into one. I think it would lead to many conflicts when creating legislature.
But what I think, is that this is the endgoal of the EU, I think they actually want to create some sort of superstate, a giant empire. They are already restricting lawmaking in the countries by creating legslature for all. They are restricting trades with countries outside of the EU( or rather support trades inbetween the EU,but that effectively leads to a disadvantage for countries outside of the EU).