Dual Citizenship May be?and you do understand that you gave up your citizenship and rights that came along with it. They are giving you OCI/PIO because you might have still members back home or have some roots/connections still to India. You might not be done with India but they can very well be done with you.
There is no obligations for them to do this OCI etc. Tell me one other country that gives something like OCI. I am not aware of any other.