Should the Italians and Germans occupied Tunisia in 1941? This would have given more airfields to attack Malta bound convoys, provided more ports for shipping, ports that were closer to the Apennine Peninsula. The addition of these ports would forced the British to hunt for shipping west of Malta, which could have helped ease the stress on Tripoli and Benghazi convoys.
Those might have proved to be advantages to the Axis, but they might have come at the cost of negative consequences that would have offset them. Tunisia was a Vichy-controlled territory at the time. If the Axis had invaded Tunisia, the Vichy regime would likely have regarded this as a breach of the 1940 armistice terms with Germany, and would probably have reacted in ways Germany would not have liked. Remember that when the Allies invaded North Africa, Germany occupied the “unoccupied” Vichy-controlled southern part of France, to which France responded with the scuttle of its fleet at Toulon to keep it out of German hands. France might have done the same thing if the Axis had walked into Tunisia in 1941, and might even have jumped to the Allied side entirely. So the cost-benefit analysis of an Axis invasion of Tunisia involves some tricky might-have-beens.