yea i guess it would make sense for places where you dont normally have your home stereo setup. kitchen or outside would be nice without wires just the speakers out there.
in an apartment where i have 5.1 in both rooms i dont see a need for speaker in other places besides having it in the bathroom.
I don't use the AirPlay out feature in my ATV1 to my home theater. I use it to my remote AirPort Express with a speaker (B&W Zeppelin) connected to it.
The nice thing is that I can be watching TV or a blu-ray in my home theater and still be streaming music to the remote speakers.
I don't use it as often anymore, but it is sometimes nice to have. I now have an old iPhone 3GS permanently on the B&W Zeppelin dock and use Home Sharing to control what music is playing.