So instead of saying "They've been lumping in European cultures together so why not Asian", wouldn't a better solution be "Let's not lump all east Asian cultures together, and let's put out material that distinguishes the various European cultures."? There's nothing to my knowledge that is preventing anyone from doing a European sourcebook that highlights the different cultures in Europe.
I'm reminded of a quote: "There are two types of people in the world--those who say "It happened to me, so why not everyone else." and "it happened to me, so I don't want anyone else to go through the same thing."