It’s a convenience.
I walk into a dark room with my hands full, I can just tell her to turn the light on. If I’m going out the door and the phone is already in my purse, I might ask her what the chance of rain is before I grab my coat. It’s especially helpful if I am cooking, and I don’t want to touch anything… she can not only set timers but read me the recipe too. And then of course controlling music is handy too, all touch-less.