Harrier's planned OSD was earlier than that of Tornado. Additionally it only had a limited RTS for single mode seeker Brimstone and no RTS for dual mode seeker Brimstone. Furthermore it could never carry Storm Shadow and its Sniper pod capability was far inferior to the Tornado's RAPTOR.
Ergo its weapons were effectively the CRV7 and PWIV.
If you were going to bin a capability to save £££ (and I'm not saying that was the right thing to do) then it made sense to keep Tornado and sack Harrier off.