I always wondered that too. When they admit that Yahweh is more correct, we should be Yahweh's Witnesses.
I know I get annoyed when I go to one of those trendy gift shops and see one of those mugs that has names on it and how they are pronounced in other countries. My name is Bill goddamnit, I don't care how you say it in Portugal or Afghanistan, you say "Bill" or you don't talk to me.
If Yahweh is correct, we better use it. I hate to hear god say goddamnit.