If it is a theater is gets Atmos for sure. Whether or not it is a dedicated theater or open media room doesn't matter. The cost delta is nominal so it just gets designed that way.

For a family room it depends on what the client wants, and the layout of the room. I ALWAYS bring it up and suggest a demo at our showroom.

I personally think Atmos is rad. I still prefer to use bluray discs when watching movies in my own media room and built it last winter in 7.2.2