Increasing the Parametric-ness of MEP Designs (Dynamo Included)

When designing MEP (mechanical, electrical, and plumbing) systems, why do we duplicate work? Why do we do things we don't have to do? We're not talking about cutting corners. We're talking about not repeating steps and taking advantage of information that's already available. In terms of MEP design, it seems like a lot of information is duplicated. For example, the loads in the building determine the size and capacity of the mechanical systems. After that, the equipment is sized, then some type of distribution system is sized, and then all of this must be documented. How would design change if we started to tie some of this information together? Revit software has the ability to do some of this, and Dynamo software can be used to fill in the gaps. When we use Revit to its full potential, and then add Dynamo to the workflow, MEP designs become more and more parametric. This in turn increases productivity and reduces time, which is what we're really after.