At lunch today I was trying to think outside the box about Laura and her role. What if Laura was sent by the giant on the side of good as a cancelling element. In other words she was a trap for Bob. Sent to draw him to her, give in to him, and thus entrap him when he takes over her body. Mike's action in throwing her the ring was not to help good, but to prevent the giants plan in serving his own purposes in his fight with Bob. She is the only thing that can stop Bob.
Not saying I believe this, but the thought did come to my mind.
I definitely think Mike is helping Coop out of self interest, not some altruistic "Higher Purpose". The Arm, too.
Laura... not sure about that but it seemed she was created with love and was definitely cherished by Senorita Dido. Even so, if she was created as bait, that's not a reflection on Lynch's view on women, just this particular one.
My belief is she was a weapon, or a counterbalance that somehow didn't work, or didn't work well enough. At any rate, she appears to have been granted some peace and happiness at the end of FWWM, which was the only happy bit in the whole movie.
Coppula eam se non posit acceptera jocularum