Why do you think some people find golly wog dolls offensive?

Hello, I don't understand why its just a doll with a black face. Why are they offensive but a black barbie isn't. Is it just black people who find it offensive or whites, asians too. I have read about shops stocking these dolls and members of the public have made a complaint to the police because they are "rascist" and they had to be removed from the shops. Whats your opinions is it racist or not and why???