With my company we started consuming a lot of hard drives lately and the question was : Why we should buy enterprise class hard drives when we can buy the same capacity for less money (desktop class hard drives) ?
because of features such as :
hard drives have firmware optimize error recovery time limits,
higher vibration tolerances,
data integrity based on end to end tolerance,
higher quality parts such as actuator magnets and faster spindle speeds.
and a lot of post on the net were based on this intel study here