It doesn't have to be cutting edge. I do some hardware/embedded SW moonlighting. Since a lot of the smaller projects seemed to have a common platform, I made a run of PC boards so I didn't have to reinvent the wheel with every new project. If I had known about the Arduino at the time I wouldn't have bothered: I'd just have used their design with my firmware and saved a bunch of time.

The point of this is to build on someone else's work. Just like I can use Apache without having to build my own webserver, I can use the Arduino design and add my customizations to it.