Whether kraut is derogatory in the same manner as yank, Pom, kiwi, etc,
The words you quote are not derogatory, but familiar. There's a war against familiarity because we're all victims, even the yanks!
racially the uk and Germany are traditionally the same,
No, they're quite different. Of course part of the same western European superethnos, English in the Germanic language group. Many common ancestors. Nevertheless quite different.
culturally they're traditionally similar.
So because places are "culturally similar" you can't be racist? That would have no doubt have been a reassurance to the millions of Poles and Russians, and Jews, murdered by Germans in the 40s, and the fellow-Anatolians murdered by Kurds and Turks throughout the 20th century.
nationalist language... Come again?
When it's referencing a white European woman (one of the most powerful people in Europe at that), I think racism is probably the incorrect term.
This ain't the 70s dude. If you think for example black people can't be racist towards whites then (like most, luckily) you lead a sheltered life.
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The thing here, that most don't want to face, is that yes it's racist, unpleasant, stupid to tar a whole group with a derogatory word. People that do this are not putting their best foot forward. And, so what? Is this this murder? No.
Petit bourgeois victim-identity fetishists will baulk not at the brittlest arguments to justify their precious righteousness.