[vinayms]

Simply because writing is the best form of communication of ideas after speech, and using speech to program is just silly, not to mention cumbersome and not productive. Writing, since its invention, has become inseparable from humans and its quite understandable that it is extended to instruct computers, with the compiler as the, well, interpreter.

As for the mechanism you talk about, that's basically declarative style and a lot of platforms (for the lack of better word) do this, mainly in business logic and scientific applications. The most famous example is Excel. However, this style works like a charm only when the set of possible actions is predetermined, and is not conducive to creating new actions, which is why every single platform has some kind of scripting. And scripting is editing text. So there you go.