Shadows depend on distance and angle. Directional light only uses angle so it most accurately mimics the sun but it only casts shadows with hard edges. You can simulate softer edges by using a shadow catcher a blur and the multiply blend mode. You can also use a point light but you will have to set the falloff to none and move it a long way away from the text layer. If you get the angle and distance right a point light will work.
however, by using the lights in AE
Why would you even? Simply duplicate the layer and distort it with a corner Pin until it looks like a shadow, then manipulate it with blurs, masks and a simple linear wipe to get correct fading and adjust its coloration and opacity.
well that is an interesting point, i figured that creating a shadow from a light would be a better way since it will animate naturally with the object and the alterations to the shape etc...would be more natural as a whole, as long as i have "light" and a "solid" placed correctly.
if i create a duplicate , then i have to manually immitate the properties of a shadow, potentially overlooking some property which i may be unaware off., but i see your point, i will try it..