I thought it was more about durability and cooling? I've had wires resting on my GPUs before due to cramp cases or just laziness on my behalf. Never had a card die because of that (I've had wires get a little burnt though haha.)
Still, the backplates made the cards look more industrial - which I'm all for.
It really has many advantages, it protects the card from both short circuits and excessive bending by making the card more rigid. But it doesn't do much for cooling, not enough dissipation area. Shaving 2$ off the BOM costs is just being cheap. Every card over 200$ should have it.