No, I don't need Hill Start Assist and yes, I know how to drive a manual.
Now that that's out of the way, listen to what you're saying: HSA is not a feature for automatic cars. How many automatics have you driven that roll backwards down a hill when your foot is off the brake? Now the Focus, with DCT, is a different animal and will roll back, which is why I gather Ford added the HSA. But traditionally, HSA has been a feature associated with manual transmission cars.
My 6MT BMW has the feature, and as I said before, it's not something I would have ever thought I would have wanted. But now living with it for the past two years, I think it's nice. And I still get to control when my car shifts. I certainly don't buy MT's for the pleasure derived from properly launching on an incline (though I can do it, I'm perfectly happy to let the car hold the brake for a fraction of a second in this case).