Re: Why are there only two cities in the future? (spoilers)
Who doesn't want to see California destroyed over and over again?
If you're going to crash kilometre-wide starships and drill holes from orbit, by all means, keep it in San Francisco, and I can hope I am safe thousands of kilometres away. Don't you even think of doing dangerous stuff elsewhere.
But if you're having fun holding a conference or inviting some hot Caitians over, now, if you don't bring it here, I'd be pretty offended.
R.I.P. Admiral James T. Kirk (2233-2267, 1969, 2267, 1930, 2267-2268, 1968, 2268-2269, Serpeidon Middle Ages, 2269, 2237, 2269-2286, 1986, 2286-2293, 2371)