We know many of you are complaining about the lack of these civs. They're still in our plans and are like 90% complete.
When we finished coding a civ, we playtest it a lot and we realized those civs were "boring" or too buggy. So, we had to take them out until we fix their errors. They're coming soon, so please be patient. The same happens to some random maps, Great War... we made them, we found bugs, and we're fixing them. Soon they will be released in a patch.
NOTE: As of June 30, The Mediterranean Patch (1.0.9c) includes the missing Italian and Maltese civilizations! Stay tuned for the rest in a future patch!