Would Crete have had any value as a forward bomber base for the Allies? That is in 1943 or 43 would it have been useful for attacking Rumanian oil refinerys or something?

It certainly would have been usefull as a fake invasion base for deception ops like Mincemeat. Perhaps another armys worth of German soldiers could have been drawn to the Balkans with commando raids and deceptive radio broadcasts from Crete.