Not sure if this is something you guys at iFixit have considered as far as environmental impact is concerned (and I could be wrong here as i don't know the process myself). If something needs to be replaced on an Apple product and is returned under warranty or Apple care then the entire unit is replaced for the customer. The defective unit is then repaired, refurbished and resold to the consumer at a refurbished price. That still results in that particular piece of technology being out there in use and not on a scrap heap.
Again I'm not sure if I am missing something in the process here but this seems like a decent way to keep technology in circulation and off the scrap heap, at least if it's covered under warranty or apple care.