It exists in nature, however humanity's usage is unnatural. Compared to plastic, aluminum is much better for the environment in electronics. Period. It is recyclable, and your example is completely out of touch with reality in that it is not used in piping or other such examples in which natural contamination occurs. Plastic biodegrades in unnatural methods, if at all for some. Would you rather Apple produce plastic devices that end up in our ecosystem for centuries, or that can be recycled at the cost of more pollution? I'd rather a natural metal that can be easily melded and reused.
No one is licking their electronics. Apple is mass producing some of the most popular consumer devices to date with materials that are far better than the plastics you claim superior. Additionally, most Apple devices are not thrown away; most are resold or recycled due to their high resale value, etc. I'd rather that than more [plastic] e-waste in our oceans and lands. I've been to many area's in which people literally walk beaches covered in plastic trash, old phone's, computer parts, wires - many in these impoverished third world nations in which we dispose of our refuse (out of sight, out of mind - grease the system and keep people spending without realizing the collective toll our capitalistic system has on the world) scour their beaches in order to reuse/sell our disposed electronics. For us it may be junk, for them it's poisonous cash that may buy them something to eat if sold to the right person without realizing how toxic it is. You'd be surprised how terrible our first world lives effect the planet and the other creatures we share it with, all because we want to keep up with the Joneses.