All of us who grew up JW have heard this argument a million times: to have a close relationship with someone you must first know them by name.
But how would you feel if your kids called you by your first name? Instead of showing a closeness, it would be looked at as a sign of disrespect. Their calling you "Father" would be the real indication of their special relationship with you.
So it is with God and so it was with those who considered the divine name too sacred to pronounce.