Soy is the most versatile food. Consider what we get from it: just plain beans, milk, tofu, tempeh, seitan. I think even liquid amino, which in my opinion tastes incredibly good and is said to be very good for you, fits in the soy category. The list goes on and on.
But, there's some controversy. If you replace milk with soy, can you effectively get enough calcium from other sources? Is too much soy actually harmful?
Then, there are little questions. Like, why is some soy on the shelf, unrefridgerated and other soy in the cooler in the store? How easy is it to (practically) make soy milk from beans?