National Identity

Actually, Europeans have a decent sense of their national history and national uniqueness. The popularity of European stereotypes about one another is evidence of that.
And Europeans have a good understanding of cultural differences between each nation.

What they lack is a racial sense of themselves, so they think anyone can be British or French because they think anyone can be European. The genetic basis for these national permutations has been removed, or to put it another way the major distinction or efficient cause has been removed.

Also the third world invasion is what is currently happening, so it is a racial and not ethnic issue. And the propaganda and deconstruction is against racial identity. And the same deconstruction you use on race is what they use on race, before they then use it on your national identities. And even if they dont, without the meaning injected by genetics people will just claim it is assimilable even when it isnt and you wont be able to test for it beyond superficial aspects or kick out people here (especially once enough come in, and they know that. See the amnesty debate). And currently any debate about genetics is on the racial level too
https://www.theguardian.com/commentisfree/2015/may/10/snp-english-national-identity-class-cultural-divide
And cultural ideas of these identities are dumb because all Englishness is is what the English are. Which can be contradictory and exclusionary (and people who shy away from race dont like to be that). The people who deny Englishness are a part of that fabric by the way, so even if you blame them and their identity politics, they exist and you cant pretend you have a way of thwarting them.
https://www.theguardian.com/uk-news/2014/may/20/england-identity-crisis-english-euro-scottish-elections-ukip-patriotism
https://www.the-tls.co.uk/articles/public/can-literature-forge-english-identity/

https://www.opendemocracy.net/blog/ourkingdom-theme/paul-kingsnorth-1/2009/05/07/response-to-a-jigsaw-state-breaking-up-britain
https://en.wikipedia.org/wiki/English_national_identity
No discreet idea of what it is

http://www.huffingtonpost.co.uk/jake-mills/english-identity_b_6876370.html
http://www.nbcnews.com/id/34152407/ns/world_news/t/great-debate-what-does-it-mean-be-french/#.Wh-q-EqnGUk
http://www.nytimes.com/2009/11/29/world/europe/29identity.html
http://blogs.reuters.com/great-debate/2015/01/16/to-become-french-leave-your-identity-behind/
http://theweek.com/articles/650116/france-having-identity-crisis
https://www.theguardian.com/world/2017/apr/22/france-elections-2017-le-pen-fillon-macron
https://www.politico.eu/article/german-identity-threat-refugees-migration-merkel/
http://www.breitbart.com/london/2017/05/17/commissioner-german-culture-doesnt-exist/

Ethnic identity requires racial identity. You need to see yourself as first more divided from the non-european spheres of the world before you can properly appreciate the unique place you're in.

And also there is no good argument against racial identity except via the strawman that we think all Europeans are interchangeable rather than desiring for us to stick together. Gone are the days where only we mattered and could kill one another out of rivalry. Also that is what has led to this mess, the wars shattered our civilizational confidence.