My own interpretation of the story is that Walker disapproves of making icons of the everyday objects that are our heritage. She approves of using everyday objects for the use for which they are intended, hence the title of her story. What makes me place this interpretation upon the story is her treatment of the characters. Walker portrays Dee with a bit of contempt and portrays Maggie lovingly. We are seeing both daughters through the eyes of their mother, but it is difficult to not perceive this perspective as Walker's.
Dee is not portrayed sympathetically in the story. Her "back to our roots" ideas are shown to be foolish, with the adoption of African names and the idea of hanging quilts on one's wall or "displaying" a butter churn. The mother makes fun of her and her boyfriend's new names and looks down on the life they lead, a life that is about as far removed from Dee's true country roots as possible. She loves Dee, but Dee has clearly always been the more difficult child, chafing against the life that the mother and Maggie are content to lead. Dee is intelligent, as we can see from her reading books to her mother and sister, but her intelligence has led her to what the mother sees as pretentiousness.
Maggie is the favored child. She is more compliant and has the same world view as the mother, that everyday objects are meant to be used for what they were made for, a quilt to cover one for warmth and a butter churn to make butter. She is contented with her lot, even though she has been crippled in the house fire, and she is more loving than the mother, actually, being willing to give Dee the quilt that has been promised to her. Her roots are no less important to her, but they manifest in a way that the mother appreciates.
In spite of Walker's take on the "worship" of everyday objects, it is something that each person must decide on his or her own. Was Dee necessarily a bad person for wanting to live an urban life or to embrace her heritage differently from her mother and sister? I don't think this is necessarily the case. The story exaggerates these different world views to make Walker's point, but we don't have to embrace Walker's point of view.
This story has particular resonance for me, since I do have a quilt made in 1872, inherited from my parents. Walker may not approve, but mine is hanging on a wall.