Reservation is justified only if it brings equality. That is, if someone lacks resources, one can give him some advantage in terms of free books, scholarship, or even a small percentage of reservation in educational institutes to let him compete with others.
It definitely doesn't mean that the one who lacks resources should get anything he doesn't deserve.
I ask a simple question. Why should we give reservations to SC/STs? Does belonging to SC/ST qualify you as a poor person? What about a brahmin who was born in poor family but still is working hard to achieve something in life? Does he deserve some encouragement? If he does, then may be SC/ST criterion of having reservations is not fair.
Secondly, I believe that the percentage of reservation should be really small (~10%) and should have a certain threshold. That is, a person in reserved category should have at least 60% to 70% capability of the person in general category.
I know hardly 0.01% people will read my comment and pay attention to it. But nonetheless it's hard to keep quite and see injustice taking place in front of your eyes.