Weeeeelll, I think they sort of have a point- 'Ohrwurm' a much funnier way of expressing the idea of "a song that gets stuck in your head" than "a song that gets stuck in your head" (cumbersome much?)

But when I think of "earworm" in English, I think of earwigs, which are clearly ickier than the German model. The literal translation of the German word fails to convey the correct English equivalent of the idea.