Well yes and no... R2 and 3PO serve the same purpose as the two peasants from Hidden Fortress, but tehy only do that in the OT. In the PT that role is completely gone. The story is NO WAY told from the perspective of the two droids, as the OT clearly was. 3PO getting built by Anakin sucks big balls, and R2 has no vital role either. In the OT he saves the day quite a few times, in the PT he kinda hangs around and tries to do funny stuff...
If George couldn't come up with a decent role for these droids, I'd say: lose them!