Why would you want to invade Australia? What possible strategic advantage would that provide?
I agree that we should employ more locations, but they also need to make sense to the plot. Somewhere like Tokyo, Moscow, Paris or even Vatican City would work, but only IF there is actually a good reason for it to happen in that particular location, otherwise you're just going "look at this pretty scenery we chose!" and leaving the player scratching their heads as to why that's at all relevant to the plot.
I agree that we should employ more locations, but they also need to make sense to the plot. Somewhere like Tokyo, Moscow, Paris or even Vatican City would work, but only IF there is actually a good reason for it to happen in that particular location, otherwise you're just going "look at this pretty scenery we chose!" and leaving the player scratching their heads as to why that's at all relevant to the plot.