Metal handle/frame means additional weight, the aluminium looks about 5-10mm in thickness, the 15/17" laptops are not light to start with, it would also transmit vibrations/bumps more than a 'pouch/sleeve" (working on similar principle) style case. You've got issues with security in the sense (as Typo said) it's pretty obvious what you have, then there's issues if you drop it or place it wrong as it could fall out easily.
It would also be expensive relative to the other types and I'd also say the handle would be painful after a while, even more so if it's reduced in thickness to reduce the weight as mentioned above.
ye it really doesn't look secure, at least with the tesco bag you can tie the handles together, hey presto the laptop doesn't fall out, and people are less likely to steal a tesco bag, who want's tesco goods when that guy over there with the aluminium case has a laptop poking right out of it?
I might not want to lug the power cables and associated "brick" with me, but once I get where I'm going Im sure I'll need to charge the thing up again. I see what you're trying to get at, minimalist "bag" to fit the minimalist design of some fruit-based notebooks, but I just don't think such a thing would be practical. Not to mention I'd want my Â£XXXX laptop to at least have SOME padding while being carried about! Plus, it looks a pretty tight fit, not all laptops are created equal... PLUS! That aluminium handle looks uncomfortable to hold over a long period, where's the shoulder strap? PLUS! I'd use a carry case for transporting a laptop in a car... what if it slid out?
It looks shiny and very "apple", but it's seriously impractical.