Kakinada is a terminus. So are MTM and NS. Termini are convenient points to handle originating trains, and that's why SCR prefers running trains from these places.
KRNT is neither a junction, nor a terminal. So, long distance originating trains are unlikely. It will be similar to Nellore/Rajahmundry/Ongole/Cuddapah etc - will have some originating trains, but will not be a preferred originating point for long distance trains.
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Besides, Hyderabad and Vijayawada are not comparable. HYB alone will fill up any train and will have far more demand to any destination than any other place in the two states. HYB-KRNT is a much more skewed comparison than BZA-COA.