Why does the poet ask questions in "Still I Rise"?

Maya Angelou, a black woman, is writing in defiance to the way white people have written about and described the black experience. She calls the white version of black history "bitter, twisted lies." She also writes to express that she is rising above white attempts to enslave and destroy black people.
To defy how white people have characterized black people, Angelou asks a series of rhetorical questions. Rhetorical questions have only one possible, very obvious answer. They are used not to invite a reader to ponder a question, but in order to emphasize a point.
Angelou hurls her rhetorical questions at white people. She asks if her "sassiness" and "sexiness" upsets them, if her "haughtiness" is offensive, and if white people want to see her broken and tearful, with a "bowed head and lowered eyes."
The obvious answer is yes, white people are offended if black people show assertiveness, sexuality, and pride. They do want to see black people broken and defeated.
However, Angelou says, she is going to persist in doing what offends and upsets white people, because by doing so she is refusing to let them define her and defeat her. No matter how many lies white people tell or cruelties they perpetrate, she will "rise" from oppression into being her own person. She doesn't want white people to be comfortable, and she asks questions that make them feel discomfort about who she is.