System Architecture Principle 4: Systems exist to solve a need

Tagline: Systems exist to solve a need (Shapira) (Crawley2010a).

Descriptive version: Systems exist because humans or organizations have a need and are willing to trade something of value for that need to be satisfied.

Prescriptive version: It is important for the system design / architect to understand the needs of the key stakeholders and design a system that satisfies those needs.  Further, the perceived benefit of the system must exceed the perceived cost to obtain and operate the system.

Discussion: In the end, systems are acquired by exchange of money or other things of value in return for the benefits of the system.  The system must provide perceived value that is greater than the perceived costs, the difference being the perceived relative benefit of the acquiring organization or person.  Note the relation to the perceptions of the acquiring person or organization; this very much is in line with the principle of good architecture, which it is in the eye of the beholder.

This model gives the architect to levers to pull in order to increase the relative perceive value.  The first is to focus on the external interfaces, external form, and external deliver function in order to increase perceived value.  The second is to manage the internal system design so as to decrease the system life cycle costs

Citations
Y. Shapira. Principles of system architecture. http://en.wikipedia.org/wiki/User:YoavShapira/Principles_of_system_architecture.

E. Crawley. Esd.34 lectures on value exchange model, 2010.