When baking a texture in Blender (or other 3D editing software) and using it in ThreeJS as a MeshBasicMaterial - it will not interact with any lighting in your scene. If you try to use a material that will (EG MeshStandardMaterial) you'll find that your baked textures don't look right - because they're being lit both during the baking and the real-time-rendering.
Using this material will allow you to have specular reflections (EG glossy or shiny textures) while still maintaining baked lighting. Here's an example of what I'm talking about:
