Why is it important to mitosis that chromosomes align at equator?

being aligned at the equator allows for the spindle fibers to connect to both side of the centromere, which allows the sister chromatids (two chromosomes that share the same centromere) to be separated during anaphase. if they are all over the place it will be hard for the spindle fibers to attach to the centromeres. the equator is roughly in the middle of the cell, this allows for an even length of fibers to reach each side of the centromeres, an uneven distribution of these spindle fibers can potentially cause uneven distributions of chromosomes in the daughter cells.