Right. The ordinance they dropped was substantial by the standards of those days, but the effect was to reduce the morale of the populations: effect was to reduce IPC by effecting the will of the people to continue the fight.
So allow them SBR capability.
Additionally, they were good fighters in the air and air units could not even reach them till latter in the war if they conducted high altitude attacks. Basically their biplanes were very slow at climbing and had a limited ceiling.