Salutaions,

I had never realised just how important the island of Melita has been to the Byzantines until you enlightened me on it.

Of course the period of 6th to 9th centuries was when Byzantium was trying to remain in control of the Mare Nostrum even if it was theoretical.
But by the year 1048 there were some lacklustre emperors who wanted easy victories to gain popularity in Byzantium, so Melita was that target, If I recall correctly part objective of the expedition under general George Maniakes in reconquering Sicily.
Such a venture was sensible, it would increase much need revenue by taxation to the crumbling Byzantine state of the post Basil II period.
As you may know from reading on the events, classic short sighted Byzantine envy led to the fall of this great general and the loss of the reconquests.

By the reign of Manuel I it was again a priority to defend the Adriatic coastline of the Empire and this meant taking the offensive against Norman held southern Italy, Sicily and Malta.

By that period the Byzantine empire was trying to be Here, There and Everywhere, it had the equally difficult problem of the Seljuk Turks in Asia Minor to deal with, and of course with the death of Manuel I there was no one equal to him to deal with such tasks...