I agree no single Polynesian nation is especially significant. Hell, all of Polynesia combined is pretty insignificant. But I don't agree they are not interesting. Their cultures are very distinctive
Zulu - pathetic very small state of very primitive tribe that lasted very short before achieving one insignificant victory against (outmanned) British and being promptly completely wiped out by the first competent expeditionary company. Zulu are the worst african "civilization" one can pick even if seeking "anti colonialism" theme (Ethiopia and Ashanti are much more impressive in this regard, as is Kongo). It is also tired cliche civ with the same playstyle in every game (super agressive infsntry!!1) and no innovation regarding its leaders or uniques is possible because it was so small and so short lived. For the love of God don't add Zulu, as recompensation add two more blck civs instead.
You are thinking only of Zulu in the time of Cetshwayo; Shaka's military campaings took place over a fairly large area of land:
I don't like how overpowered he was in Civ V though; demonstrated very well his reverse colonisation of weaker European Civs. And I would not really mind if Zulu did not appear in Civ V; I actually wouldn't mind seeing Mandela, though he is likely too recent, so I doubt we'll be seeing him any time soon. Also, Shaka is something of a staple of the series, being in the games from the begging, and so in line with the inclusion of Gandhi, Shaka would seem plausible.
5) Huns - what's the difference between them and barbarians? Plus there are many other more nuanced varied or interesting nomad cultures that have depth beyond 'raze'. Plus the idea with their city lists was atrocious and immersion breaking. Plus they are already dead anyway because their entire niche got filled with Scythia.
The difference between Attila's empire and other 'barbarian' nations like vandals, goths, etc., is the scale of his dominion. He was something of a 'barbarian' emperor. As for Scythia; Tomyris is not really suitable as a substitute for Atilla the Hun; she may have beaten a great empire in war, but did not herself rule a kingdom near the scale of the empire of Attila, or engage in conquests the likes of which Attila did. But it is true that her game-play (even if it makes little sense) is akin to what you would expect from a Hunnic Civ, so we could well not see Huns again.
Venice (Italy needs some representation but this one city weirdo was failed experiment).
Except that IRL, Venetian republic ruled a lot more than a single city. Also I feel that the Romans, contrary to whatever you want to think, are just fine as Italian representation; just because modern Italy is not particularly more related to ancient Rome than other European nations biologically, does not mean that it does not suffice as representation- many Italians see the history of Rome as a very significant part in the history of their own nation. Other Europeans who were ruled by the Romans in most cases see them more as foreign invaders.
And as you earlier pointed out when you said we don't need Gauls and France; the territorial overlap is unnecessary.