I think political union should be broken down according to societies that share the same culture, language and where there are practical gains in sharing a macro economic system.
This is where we differ on principle. You seem to regard these as somehow insurmountable differences that divide "us" from "them". I regard them as practical obstacles that we should endeavour to overcome. I regard "us and them" thinking as undesirable and counterproductive. I think we should work towards as much unity as possible between the largest numbers possible.
Are you going to be consistent, if we stay and the EU signs us up for TTIP should the US\Euro have political union?
I'm sure we could start an entire separate discussion on TTIP and I think EU/US unity isn't going to happen any time soon. However; is it goal that we should aspire to in the long term? Yes.
As an aside, I have spent some time working in Germany, in the offices of a German owned multinational, and I felt quite at home; I found no great cultural divide. Sure, their native language was different but, interestingly, the only language requirement for working there was English.