Default Requestors ship to from requisition on PO Header. Why must the buyer select.

I would like the requestors location to default to the Ship to location on the header of the PO when a PO is created freopm a requisition from Autocreate screen. 

From what I read it defaults based on Fin Options and if thats blank gets from the Supplier Site Defaults.

Ideally I need the ship to to default to the requestors location (defaulting line rules). Seems the documentation says that ity will default to the Requestors location on the line itself ie the distribution line. Why not the header whats the thinking there.

Any held would be much appreciated

Thanks