They could, yes, but it undermines the fundamental basis on which the consumer PC industry is based: cheap, throw-away computers.  Well-designed machines require precision and machining that adds to the cost of the computer, and with companies such as Dell, HP, Lenovo, and such operating on such thin margin, high-volume selling, any additional cost adds up quickly.<p>There is a massive difference in the build quality between a typical Apple product and a typical HP or Dell product.  There's an attention to detail that appears to only exist at the higher price point.  For those that build their own boxes, you have likely found that a quality case is worth the price differential — and this is only one piece.