Only for fun
To me it wouldn't make sense to have a huge pc doing router work in a home environment, other then for a hobby. In case you have a SOHO and need to store/transfer a lot of very confidential data, it might make more sense, but still: with a regular DD-WRT Mega Pack powedered router, a lot is possible. I don't recognize the instability issues that have been mentioned before; once the routers are flashed well, they work flawlessly (at least: the ones that I've flashed). Also users talk about 50 devices connected. Which family has 50 computers connected!? Want to run a backup command center for NASA as a hobby??
If, with a bit more hardware capacity, we could add an extensive file sharing, web and print server, it would start to be a lot more interesting and more worth while having a full pc running. But still I don't understand why people need all those extra options so badly, personally I don't feel like I'm missing out on anything.
At best, I might look into VPN bridges later on, when the government really wants to spy on every citizen. At least I know my Linksys router will be able to handle that.
All together: nice article though!