In this case I agree is in bad taste, but the context sure is there, the character is not defined by her color but she is still black, if anything as someone said she should also painted her hair.
And I get what you are saying about the roots of the blackface, I am mexican myself and our bronze race had to endure all the pain, suffering, humilliation and slavery your has, such were the consequences of the clash of different cultures in the new world. But I think that if we react negativelly at the first person shouting "fire in the theatre" we wil never outgrow all our fears and insecurities, by now we all should be able to judge things according to the reasons behind it, even by going by the dictionaire this is not blackface, one of the main characteristics of blackface is being accompanied by a performance stereotyping them as buffoons which is complete absent here, all the traits were taken exclusively from the character itself and not as a generalization of black people