Board Thread:Questions and Answers/@comment-25322628-20200702024128/@comment-25322628-20200829033811

The legs are next to useless, despite their being larger than the Wall Titans because there's no muscles or nerves on them. It uses the enlarged ribcage as its primary means of locomotion, as the ends of the ribs act like the legs of a centipede.

Even if you could control other Titans, your Titan body needs to be in some shape that is a combination of strength, speed and defense. If you can't defend yourself, you're just a large target.