I don't see what's wrong with such shirts if you know the language decently. But if you don't know the language and they aren't 100% obvious tourist shirts, I find it more dubious. Everybody thinks English (not Engrish) prints on T-shirts are perfectly OK everywhere, so why wouldn't other languages be? I think denying the right to use them is elitist weeabooism as much as wearing them ignorantly is popular weeabooism.