Forget for a moment the limits of 1980s toy technology, and instead immerse yourself in a world where massive robotic creatures can transfigure their shape at will.
Voltron: Lion Force was composed of five vehicles and five pilots. All five were lions (discounting the failure that was vehicle-voltron), and while these were capable war machines in their own right their true power was only realized when they combined to create the Defender of the Universe, Voltron.
I always did wonder why there was such an enthusiastic shout of "...and I'll form the head..." each time Voltron was assembled. I assume it's symbolic, with the leader of the force - the figurative head of the team - also serving as the literal head of the composite form robot. But is it required?
If the construction of the robots were such that they only fit one way, as the toys themselves were, then there was absolutely no reason to announce this with every transformation and Keith was either an idiot for repeating this routine or a dick for rubbing his rank in the faces of his supposed teammates he was working alongside with. I'd like to think that if these robots could alter their shape, and unlike a gestalt such as the Constructicon's Devastator all pieces were essentially identical, they simply needed to coordinate which of these lions would become the foot and which would become the arm, and which...of course...would form the head.
But what if Keith were just drunk one day? Or if he just felt like being a dick? Literally as well as figuratively, I suppose? Mr. Black Lion could easily should out "and I'll form....the BALL SACK!" The rest of the team would bury their heads into their collective palms as the mightiest of lions, the giant black lion, would then transform itself into a mighty black shaft affixed to the robot's waist. This, of course, would never be shown on TV but it would have had to been attempted in testing at some point. You know how engineers are.
At that point somebody - perhaps a flustered Princess Allura - will stammer out that fine, if the boys will be like that then SHE'LL form the head. What happens then, let's say? Does the robot still look like a mighty, muscular, manly machine? Only a royal shade of blue? Or...as an homage to it's female pilot, does the torso take on a more feminine appearance itself with widened hips, a slimmer waist, pronounced bust, and finally revealing a cute femmebot face upon it's slender, graceful shoulders? Worse yet, with Keith goofing off and one of the other pilots having to cover for him rather than serving their original function, we would then have a one-armed Voltrene with a big black hard-on.
On the plus side? No space pirate or evil alien prince would want to fight something like that. One look at Earth's mightiest hermaphrobot amputee and they'd likely just turn around and find another planet to invade.