Modern plastic composites with carbon fiber / glass fibers can perform as well or better than metals with regard to strength-to-weight. Plastics also have many other properties that make it preferable for a laptop case. Apple have chosen aluminium to give the impression of build quality. The competition are too often judged by their plastic cases instead of other attributes, such as the lack of glued-in batteries and unreplaceable components.
> Apple have chosen aluminium to give the impression of build quality.
My MBP is going on 6 years old and I have not been gentle with it. In fact I have dropped it on concrete multiple times. It is dented and scraped, the hinge is crooked. It still works perfectly. My previous, plastic laptop (also a Mac) had to have its shell replaced twice (under warranty) in less time than that.
You may feel that aluminum is not worth the trade-offs or the cost, and that's fine, but I want to be clear, the MBP's build quality is not just a shiny facade.
