I agree with the other editors in posts #2 and #3 - it is clear that, although the reason Dee gives may be a factor in her decision to change her name, the real reason is that changing her name and giving herself a new identity gives her a chance to escape from the background of poverty and her childhood that she is so ashamed of. It is an act of liberation for herself so that she can become the person she wants to be without having to worry about her background and the problems that she has with Maggie and Mama.
Good question for the discussion board.
No, I do not believe Dee's given is the only reason OR the main reason she changed her name to a traditional African one. Dee despised her upbringing, although she genuinely loved her mother. She resented being poor and living the way she had to when she was growing up, although she had enough food to eat, clothes to wear, and a loving mother and sister. When their original house burned to the ground, Dee glared at the fire, apparently happy to see it destroyed. I have always believed that Dee deliberately set that fire, although it is not mentioned in the story. I would not doubt for a second that she was capable of doing so. She is vindictive and spiteful, in my opinion, so I believe Dee changed her name to distance herself from her immediate family and her upbringing.
Dee gives this reason for changing her name: " I couldn't bear it any longer, being named after the people who oppress me."
Do I think that is the only reason? No. Her mother is a strong woman. It isn't just to escape the hands of an oppressive white society that Dee changes her name to Wangero. Instead, it is also to escape her mother's powerful hand.
Independent of that, she's a young woman. Young people often want to make a fresh start, and a new name is a good way to do that.