Apart from cost saving I think the reason for the choice of Alivio over Deore drivetrain could be the compatibility with the Sora STI's. As far as I know all the 10 speed Deore parts use the Dynasys standard, and is not compatible with any STI's, where as the 9 speed Alivio parts use the mega-9 standard which the 9 speed Sora also use.

Other than that, I dont understand why they went with the alu fork, and that front rack is just thideous, and looks like something welded together of old scraps in a shed.