I guess most of us are confused with this judgement, if the reservation system is used to placate any community based on religion(example christians and muslims given reservation coz they are a minority) it is completely wrong and not a progressive step. However if there are segments in the society which are backward due to 1)They belong to a region which historically was not exposed to mainstream life - eg tribal belts 2)The community suffered historical injustices - Lowercaste communities being ripped off by uppercaste in few villages , not allowed to study in schools operated by uppercastes,
these segments of people does qualify for reservation. The OBC group is meant to be representative of this social reality.