These days homes may have many client computers. There is a need for small cheap home servers for backup, file-serving, collaboration, etc.
“If you’ve got several different computers in need of a consistent and automated backup strategy, the RPi can do that. If you have music and video you’d like to be able to access from almost any screen in the house, the RPi can make that happen too. Maybe you have a printer or two you’d like to share with everyone easily? The Raspberry Pi can fill all those needs with a minimal investment in hardware and time.”
This thing’s so small and cheap it pays for itself in a year just on the power-savings compared to using a legacy PC to do the job. How is it imperfect? Hmmm… If the clientele were a bunch of legacy PCs, you could probably accomplish the same thing by having at least one available 24×7. You could script a virtual server to do the job when any machine is up. If they are all down, then you don’t need a server except to synch with the outside world. So, a backup system could be made from a distributed file-system on a cluster and file-serving could be made from a distributed file-system etc., but then one would be wasting storage rather than electrical power and space. So, it’s nearly perfect… 😉