Bruce Jenner can change his own body all he wants, dress how he wants, be intimate with who he wants, but we should draw the line when other people are put in harms way. We should not let men put a baby into harms way by trying to be a mother to a baby, either with a womb transplant or with stem cells, artificial eggs, etc. It would also strain our hospitals, divert resources from other women's pregnancies and children, and divert research from needed medicine, and there is no right to try it.
The exact same logic applies to same-sex couples trying to create a baby together. When we realize that, we will understand why same-sex couples do not have a right to marry and we have to void all same-sex marriages.