That sounds great in theory, but it will take decades to make significant improvements in agricultural productivity (mostly for political reasons) and preventing mass starvation in the mean time is also important.
The PDS system creates a floor price for agricultural produce, ensuring against the vagaries of the market. At th same time it distorts market prices.
Given the inefficiency in the system, and it's lack of gearage which can transmit efficiency benefits to the bottom of the pyramid, the PDS system is an interim measure to help pull the bottom out of poverty.
But the point is this hunger stories reappear after the aid exhausts out. Which means people are not put to work to afford it.