Well, I think this is one of the "gatchas" in an idea like this. The malleable system you're talking about is only "a bit malleable", you can take it's elements and add a bit more. This is something like a "producer-consumer" model. To build a small or a medium-sized system from such standard elements is now reasonably simple - the original component set seems malleable. But once you've built your medium-sized system, changing it actually becomes hard, the resulting product is no longer malleable.