It’s the answer to a question that you didn’t even know anyone had asked. [LINK]
Referencing an online article about the action figure incarnation of Max, Brandon insisted that Max was never ever supposed to have legs. And you know what, he’s absolutely right.
Schematic artwork defining how Max could possibly work made it clear he doesn’t have shoulders. The limbs begin at the base. This early plan was to have two performers crammed inside Max. This eventually changed to a single performer inside.
Having a single person inside the finished costume affected the performance. When no one is in the Max costume, the limbs bend in such a way to resemble legs. When someone is in it, the legs can’t help but change shape to resemble arms, because arms are being used to operate them. The peculiar hinging of the limbs — the upward slant of femurs to knee to shins — instead became lateral slants of humerus to elbow to forearms.
Cliff Notes version: the way the character is seen in the movie and all subsequent merchandising is wrong, because of the compromise of having only a single operator in the suit.