I can be a joe computer user,
I don't like cable TV, I archive my media. I have a nice media center pc I have in my living room, which is huge, loud, and consumes a ton of power, and has been in operation for a very long time, still runs first generation DDR. I don't mind old, overbuilt, reliable noisy stuff.
But I decided to put a smaller lcd tv in the bedroom... obviously my wife can't handle noise and blinkylights while she sleeps, and I couldn't handle finding a small but awesome smart tv for a good price that would play all my media formats.
Turns out the raspberry pi plus a cheap normal tv was the best way to have a zero noise, cool running, awesome media center that shreds 1080p video. It hid easily behind the TV, is powered by the USB port on the TV, so there's only one cord running to the TV - power.
Setup took minimal work, and it's been a huge benefit to our everyday lives.
I ran the main media center with a mysql server so the libraries sync, taking additional load off the raspberry pi.
Sure, "Joe" might not be able to figure that out, but i bet he could put openelec on an SD card and get it connected to his appliance NAS pretty easily?
My parents have an appliance that's similar. It'll play XVID stuff from a NAS, probably h264, but it'd probably freak if you tried to play an mkv container. It was a prepackaged black box that's expensive as the pi, but it's slow, there's no plugins, and not even close to as capable as xbmc.
And guess what, it makes freaky high pitched electronoises because it's built with chinese caps and junk, so there's no way it could live in a nice quiet bedroom. The pi is a nice board that simply morphs itself into that role as easy as a premade device, because it's open.
The previous things i've done with a pi have included building full-time car dashboards and tuning analysis systems for my vehicle projects, to avoid having to lug a laptop around. Sure, didn't NEED to build a pi into my car, but once it was done, it really belonged there. It was cheap, i could leave it on overnight and not drain my car battery, and i could SSH to my car from my living room to retrieve and analyze logs. It also kicked me in the butt and got me coding again, which was great.
These are things that small, open, low power consumption, passively cooled, and have lots of ways to connect shit really come in handy, even for someone that isn't a hardcore hobbyist.