Line types for PR/PO from Work Order

I have been trying to find a way to default an "Amount" based line type on PRs and POs when an outside service is being requested on a Work Order.  Currently, if someone uses a description direct item type, and it is for a service, it creates the requisition with a line type of goods.  I have tried removing the default line type in purchasing options, creating and OSP item, creating a NS Direct item...all of which still seem to push it through the requisition state with a "Goods" line type. 

I understand that on the WO, it has been donned the title "Material Requirements" which would indicate the use should be for "Materials".  What seems counter-intuitive is that on the work order, you can choose the purchasing category, but not the line type.  It still goes through a requisition state, so why can you not indicate a line type up front?  Obviously, you can create a separate requisition and tie it back to the WO, but when we are trying to gain traction with user acceptance of EAM, this can be somewhat of a deterrent.