Question: What is the point of including a weakness like the crotch vulnerable spot on your robot? Ivan opened himself up for that one.
Question: I've heard this movie contains subliminal images and messages. Is this true and if it is, what are they?
Answer: It is true. The director spliced in a few frames of later scenes in the film throughout the film to "help" the viewer figure out the ending. These frames went by so quickly, the viewers couldn't really see them, but the director thought that maybe the subconscious mind would pick up on these clues.
Answer: There's never a "point" to including a weakspot, by definition they are a flaw in the design that is either unforeseen or unavoidable. Maybe they could not find a way round it when building the robot, or any solutions simply created other weakspots.