The PA Bike Routes (3 East/West, 4 North/South and one diagonal in the Philly area) are designated by the State of PA as touring routes, and are generally designed to take a rider the length (or width) of the State.
What I have been told is that for whatever reasons, PA Routes ALWAYS follow a State Route or a TRAIL. They will not route along local roads.
Where a trail is available they will use it. Bike Route A is shifted from Route 51 to the Montour Trail at Groveton, for example, and a portion of Bike Route S in the western part of the State follows the Great Allegheny Passage.
Are there roughly parallel trails in the middle part of the State that can be accessed from an existing route? If so, let's suggest a route revision to the State.