HOW IS THAT RACIST?

I just don't get it. I don't understand why a man from China would be offended if referred to as a Chinaman. After all, you call a man from England..an Englishman. You call a man from France a Frenchman... for that matter you call a man from Germany...GerMAN. Johnny Molson of Molson and Lee tried to explain it to me. Listen here.