When Nero was atacking Starfleet HQ why didn't he launch his missiles all across earths major cities just in case he failed in destroying earth? A scorched earth policy so to speak. That's what I would have done anyway.
... because he was a stupid, one dimensional villain who's motivation didn't make any sense at all.
And he's a copycat! The Dominion already attacked San Francisco. Or will have attacked, whatever, frakkin temporal mechanics. At least we managed to hit the bridge.