And the progression from taking it seriously in Discovery, as a mask of insecurity, to a more secure place in future shows, makes perfect sense, as their identity evolves over time.
The difference with the Romulans is that were always isolated, so the metaphor doesn't work. It works here very, very well in my opinion when T'Kuvma speaks to his followers after the Federation "comes in peace." Just as the alt-right doesn't care about peace with other cultures, they want to remain white, no immigrants soiling their territory, let alone their blood.
I think an even more interesting story would be a Federation world voting to leave the Federation. Maybe this world feels they're getting the short end of the stick of the alliance economically. Maybe a crisis on Andoria leads this world to other worlds pitching in to help, and this world feels like the other worlds in the Federation are getting more out of it than they are. Perhaps a new planet-- a sworn enemy of theirs-- applies for membership.
It could be a good metaphor for nationalism and Brexit.