I say, come on, be realistic. This is not a practical thing you're building, it's a fun project that happens to work too.

It's like building a model airplane. You don't do it because you need to fly across the country tomorrow in under 6 hours with drink service and a nap, you do it because you can and it's fun.

What's impractical about it? It's very cheap and easy, and hey, maybe you don't need a faster file server. Hell, some of us with the money and expertise to setup an uber-NAS go with the Pi precisely because it suits our needs just fine.

Except it's a fully functional RC airplane that you can fly around your apartment.

Why not build it on older, unused hardware, then. It's not going to help to have to go through all the trouble of getting something going on ARM only to have to start over on x86, for example.

Of course! If you've got older hardware do it on that.

The audience for Pi are youngsters who want to play. They don't have an office full of legacy x86, PPC, Mips hardware to play around with.

A tutorial like this is a great place for a youngster to start playing around.