system
Given the following post, respond as if you're commenting on Reddit:
human
[General] Why do nearly all beings, from alien to robot to monster, store critical components in their topmost extremity?

It seems that battle robots, at least, would be built with a decoy 'head' that can be lost with almost no repercussions. The instincts of many creatures would misfire if the head was a non-vital component.
gpt
Physics plays a role.  
Signals only propagate so fast, so it behooves a creature for its sensory organs/devices to be as close as possible to its central processing apparatus.  It is also advantageous for sensory organs to be on extremities, particularly elevated ones.  
Combine those two things, and you get 'brains' in 'heads' a lot, because they 'eyes' are also in the 'head'.