>>62194737REX is new technology who's main engineering problem is the weight of the payload, it's not actually intended for fighting in AP role and using it that way would genuinely turn into a dorky boss battle, particularly if the moron in control of it decided to activate it while it was still indoors. You know, because he's a raging maniac backed into a corner. RAY meanwhile is meant to move in water, it looks dumb on land because it is dumb on land, it's movement capabilities being roughly that of a penguin.
So we have dog thing that is one step above being a very large truck and a penguin minus water. Being piloted by two old men who eventually just get out and repeatedly inject nano-crack while screaming and punching each other and I love it and it's one of the best scenes in a game.