Thanks guys.
Yes, seems right to switch them off on air/ground logic.
This tragic accident apparently started in the aft cargo. The write up states as a possible reason - "Typical causes of Class D cargo compartment fires included baggage contacting airplane electrical components such as lights, and items being carried in passenger baggage or mailbags."
Air/ground logic is sound, but wouldn't it be safer if the light were switched off when the cargo doors were locked? What could be the reason to leave them on while the aircraft is still on the ground - waiting at the gates, taxiing, holding, etc.?