I just think Aluminum material is scratched easily. Eventually, it will worn down, be scratched. Even you put a lot of protection on it. Hard shell case itself can scratch you laptop as well. If you say yours doesn't have any scratch, you did not look closely and well enough.
I have heard liquid metal is the way to go. But when?
Other than the elusive and vaporous liquid metal, what material do you think would be better than CNC machined aluminum billet? I've had MacBook Pros and PowerBooks before them, including Titanium PowerBooks and Powerbooks made of various plastics including glass-filled resins. I've also had laptops from other manufacturers made mostly of plastic. Not one of them as nearly as solid and elegant as a unibody MacBook.
I spent some time in the Fry's laptop department this past Sunday looking at the current state-of-the-art from Sony, HP, Toshiba, Asus and others. Frankly they all ( and I do mean ALL) pale in comparison to the build quality and elegant feel of a unibody MacBook Pro. Particularly the MBPr. Even machines that are obviously designed to look like aluminum MacBooks (the new Asus and Viao Signature, for example) just look and feel... cheap... when you get close to them and actually work with them.
I schlep my MacBook Pro's all around the world in a carry-on briefcase and I use it the better part of the day every day. I did watch a colleague drop a video projector on my MBP a couple of years ago, which resulted in a dent in the lid. And I've managed to put the occasional minor blemish on the bottom panel by setting the thing on uneven metallic surfaces. I even once set the MBP up on lava rock in Fiji, which did produce a noticeable scratch on the bottom panel. Duh. But honestly the unibody Macs hold up amazingly well. Rarely do I scratch them.
So again, please name some other material or manufacturing technique used by any other manufacturer that's more durable than a unibody MacBook.
[Before you go there... I'll acknowledge that the Panasonic Toughbooks are pretty darned durable. Ugly as grandpa's toenails, but durable. But really. Who wants to shlep one of those around.]