Why are maintenance and reengineering so important for both software engineering managers and practitioners?

1. Senior managers who define the business issues that often have a significant influence on the project.

2. Project (technical) managers who must plan, motivate, organize, and control the practitioners who do software work.
3. Practitioners who deliver the technical skills that are necessary to engineer a product or application.
4. Customers who specify the requirements for the software to be engineered and other stakeholders who have a peripheral interest in the outcome.
5. End users who interact with the software once it is released for production use.