most cities are "New York" huge? no lol. no where close. im sure things are different in the UK, but here in america (where the game takes place), the overwhelming majority of cities are small. we only have a few big (land) cities, a lot of our cities are smaller than the entire map of san andreas.
Another thing i thought of is, with gta4, they said they were making an exact replica of NYC. gta games are known to consist of connected islands that open up as the game progresses. if they are planning to make an exact replica of LA, how are they gonna do the "islands" system?