Well, I have to say, for an inexpensive low-end server / NAS, Atoms make a LOT of sense. I've just set up one of these:
Runs CentOS 5.5 x64 with 4 GB of RAM and provides me with:
- Samba storage
- Full featured Apache web server
- Mail server, webmail
- TeamSpeak 3 Server
And a ton of other functionalities related to Web Services. Not bad for a tiny in-order dual core which draws 35 W fully equipped. (I still run it from a cheapo 450 W PSU, so power will drop even more with an adequate, efficient unit).
What reason would I need to buy more power hungry equipment? Well, none, except for maybe opening up an ISP business. And even then, you could find some use for low end Atom-based dedicated servers.