There is a history behind both blackface and women stereotypes that negates what you say.
Lets just say two white men portray black women acting like hoodrats. That perpetuates stereotypes that run back into the Jim Crow era, perpetuating the sapphire (from Amos and Andy) stereotype of black women. This stereotype- headstrong, sexually liberal women lacking morals, perpetuates the notion that justified the white man's rape of our foremothers. Slave owners justified their black lovers and offspring by creating a narrative that made black women into hypersexual beings. The loudness comes from the mammy stereotype, who could be loud and loving, and the strong black woman, who is too strong to know her place in a man's society.
Black men portraying white women brings up no such history. There have never been negative stereotypes thrown out en masse by black people to oppress white women. Or white people for that matter.
So it aint the same