Prasadji, you have misunderstood me. Suppose there are x number of seats vaccant, and I book n number seats and get my confirmed reservation. I come to know of my seats/births only after the seat/birth is allotted. The only consolation is you are allowed to say whether you want window seat or lower birth etc. But what happens when a family of five goes, you are not allowed to book continuously all the seats which would allow me to stay and travel together as a family. Normally the lower births are allotted to tatkal passengers and not allotted to regular bookins, likewise, the window seats/births, one is shared between two RAC waitlisted passengers. So for a family travelling together in the same compartment and stay united is a bit difficult. Also, seats/births in Non-Ac compartments near entrance is a hell of a problem with outsiders boarding and occupying the seats during day time and the worst smell of lavotory and also the fear of our belongings being stolen.
So, If the Traveler is given a chance to choose the seats as per his convenience, then the Traveler is pretty sure of his comforts. The railway is not going to loose any income. May be they can charge a bit more for advance seat selection.
Also the Railways must ensure that no unauthorised person travels in the reserved compartments even during day time. It is a ugly menace nowadays in all reserved fast/superfast trains.