Train need not run on shortest route but there is no point having it run on the longest route. If it is on longest route, it serves no purpose for people of Originating station and Destination station. Only some in-between station passengers will benefit. Especially when there is no direct train previously and this is the first train between Hyderabad and Mangalore, it makes all the more sense to have it on a shorter route. Who wants to waste their precious time on a loooong route??