संपूर्ण क्रान्ति है तो जहां है

It saves 15km, avoids Tenali station (which does not have many through lines) and the sharp curve outside Tenali towards GNT side which, for a freight train, can mean cutting down an hour of travel. The chord line also has a much better alignment than the route via Tenali, which would make it a preferred choice.
Also, it will effectively double the capacity between BZA-TEL/Tsunduru. When the chord line was opened, it was supposed to let SR use the BZA-GNT-Tsunduru line as a second line (the BZA-TEL route was still a single line), effectively making it a double line between BZA-Tsunduru. In the same way, now it will effectively make it a quadruple line.
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the ~10km chord line can be completed much faster than the tripling of the route. So, this might actually be something they'll consider seriously.
As to the Vejendla-Tenali section, it will still be used by passenger trains, and they might as well double it instead of leaving it as a single line.