It's not just sex that needs to be rethought, it's also gender roles.  One buttresses the other and current teaching on both buttress the priesthood.  In the end it's the teachings on the priesthood and the teaching authority of the magisterium that's being sustained by the refusal to reconsider Catholic teaching on sex and gender.  Better to ignore the fact the laity don't follow the teachings on sex and gender because to acknowledge this is to pull the card that topples the whole house of cards.