splitting of nation and country states is not a new thing - it has happened all through history and for all sorts of reasons. the most common reason ofcourse is influential leaders clashing for positions of power. How they acquire such influence? religion, trade, race, physical might, blackmail, personality etc. In this case Jinnah and few others used religion.
Has partition made India and Pakistan less? Without doubt, because the two waste resources against each other. The Islamic religion is used as the fuel for sustaining this dispute.
Irony is the most common perpetual thing, next to time and karma. In this case the very factor that was used to create the two sides continues to be abused to keep them both in conflict.
Muslims certainly have suffered due to this but a majority of their sufferings are not due to the splitting of nations but rather due to other misguided notions.
It is incontrovertible that Hindus on India and Pakistan have borne the predominant brunt of partition.