What are Issues of Transforming Robots or Robots that Combine into Bigger Mechs?

[Disliker of the mary sue]

Originally Posted by Johnny1A.2

. Humanoid transforming and combining mecha make no sense for any purpose other than Coolness, and like most Cool things, they make no sense when looked at coldly.

Hm interesting, The only justification for human like giant robots I found I liked is that in systems like in pacfic rim where you control the robot with your body/mind, that it easier for the human mind to grasp the idea to walk like a human rather then having to learn an entirely different method of walking. But brain controlled machinery seems to be a thing that won't be a thing before at least tl 9 to above if it even a thing that is possible.