Ya Right.
The importance of local people if extended to BSB can't be ignored at all.But this must take the Shortest route to BSB from LKO (Jaunpur,Sultanpur,Nihalgarh).
The interest of Farthest passengers are also important as well.
If it is Extended to BSB, people can divert from MGS to Patna/NJP/Bhagalpur/Dhanbad/Howrah/Kharagpur easily by any other connecting train.