Beneatha does not outwardly respect her brother Walter. This is the source of their inter-personal conflict, in large part, and is also the source of Walter's internal conflict.
Although he is in his mid-thirties, his living situation encourages him to believe he is perceived nearly as a child.
Walter resents his position as a servant, driving a car for someone else, and wants to do something that will bring dignity to his family and to his position. He wants to be proud of himself so that his family can be proud of him.
In the end, he achieves this goal but not in the way he expected. Though Mama often tells Walter in various ways that he should be proud of his family as it is, Walter must be pushed to the lower limits of his sense of self-value to finally take hold of the pride that Mama has said was available to him all the time.
By standing up to Karl Lindner when it would have been easier to accept Lindner's financial offer, Walter asserts himself forcefully into his culture—and although his choices may make his life difficult in some ways, he will not be spiritually defeated.
In this culmiation of the play, we see the importance of self-value and self-concept. Returning to Beneatha, we can see clearly now how troubling Walter's views of Beneatha's disrespect and disregard are for him. These negative interpretations of his character touch his greatest weakness and deepest chagrin.
Thus Beneatha's views of Walter are quite important to his views of himself and to the conflicts of his character.