I think you're asking for the holy grail here. Everyone would love to have such a thing but nobody thinks it's likely to be possible.

So they settle for much smaller targets. Either of understanding how much simpler systems work. Or of trying to understand a little bit the effect of tweaking something in some more complicated model.

Perhaps you should think of these two approaches as analogous to doing simple chemistry (what shape is a sugar molecule? A DNA molecule?) vs trying out drugs (if you eat the bark of this tree, you don't get malaria! Let's refine that stuff). Both can be useful, but they are very far from a unified theory of how your body works.