I always figured some of it has to do with weight savings too. Every little bit of weight saved helps with CAFE.

Recently removed headlight molding, grill, and headlights from my '79 Power Wagon. Not one single piece of plastic involved. Just a bunch of metal screws and metal pieces. What a pleasant experience. Same goes for removing the door panels to grease up some internal parts. Metal clips, screws, bolt for handle and window crank. So nice.