[BubRoss]

That's because they work on the same data format, have no state, no branching, single input, single output and can be executed serially without needing to be looped. They also don't have dependency problems when installed as a distribution. If that wasn't enough, you can examine each stage by writing it to a file or piping it to display program of your choice.

If they work for what you are doing then using commands and pipes are great, because they avoid a tremendous amount of what makes software difficult.