I don't have much experience in vray or lighting, but to take a stab at it: Maybe try using a large area light instead of a sun. It might give you that softer lighting that you're looking for. I think commercial photography rarely use raw, direct sunlight; it's almost always modified with diffusers/scrims, or just staged…
My first thought would be to darken the diffuse color way down, but I don't have experience with this particular use case to know if it'll do what you want.