Now that's just silly talk. Aluminum is nowhere NEAR being the "one of the strongest metals around". It can be used to produce strong structures, but only when there is a lot of it, it is used as an engineered extrusion, or it is cast or forged. A stamped phone cover, or even a machined unibody is much less durable than plastic, let alone steel, carbon fiber, or titanium. Aluminum will not bend and return to it's original shape the way plastic can. Aluminum cannot take take an impact with denting. Think of how easy it is to crush an aluminum can. The same structure molded out of ABS plastic would be much more resilient to being crushed and would even provide some springback. Think of an aluminum bodied Acura NSX that will dent if you breath on it wrong.You do realize that Aluminum is one of the strongest metals around right? Though not in the top 10, it's much stronger than the plastic you find in phones.