Tofu is a nice protein alternative to meat. However it can be quite bland and soft. That's why it's nice to use some soy sauce and sesame oil and bake it crispy.
Because when baking in a pan, the tofu can stick to the pan. When moving the tofu pieces rip apart.
When the water is still in the outside of the tofu, tasteful fluids like soy sauce are not soaked up well. Also without the water, the outside can be baked crispier.
The starch makes the edges extra crispy. Idea from The Kitchn.