It's part of the "UNIX philosophy" - to write programs that do one thing, and do it well. They also encouraged the use of text interfaces so that it was easy to

It's part of the "UNIX philosophy" - to write programs that do one thing, and do it well. They also encouraged the use of text interfaces so that it was easy to connect pieces together with pipes. Text was seen as a "universal" way to transmit data. Such a universal protocol is another concept I think will become more important as the web continues to grow.