There are many factors that we may prevent reuse of a component.
From purely aesthetic reasons, functional aspects, need for innovation.
Getting to decide whether to reuse a component from our library or component provided by a module is an architectural decision.
It is certainly an advantage that time comes, they will have the option to innovate but the re-use.
Without a good system without a good film and architecture, the second option would not be possible.
At the level of modules and other Drupal direct line of action should be to cooperate, but for now, until we standardize a system that allows entities compartment institutions reuse the same way that modules are reused, must be own internal hierarchy of each department that manages these components self.
Certainly a good course of action for the future of Drupal is to increase the functionality of the modules with the most common components, as have the location module, for surely it will create a module named person or people, allowing deployment all the characteristics of the individual.
Given this lack, the creation of individual component, to us, then we must decide whether all our sites must use it or there are some who would use only some characteristics.
The range of possibilities is endless.
We talked about so many other important architectural decisions that focus on project success and the success of an agile methodology components.