Oh, sometimes we need them in Texas. During the winter, it will occasionally get colder here than in Michigan or southern Canada. But no, they're not a regular-use item.
That said, I have my Pathfinder kitted out with most of the cold-weather gear that Nissan offered - block heater included. I figure it should be a "go anywhere anytime" vehicle.
The "experts" claim you should use the block heater if it's below -10 C. And it does save the engine from a lot of wear and tear.