Why is the initial requirements definition process so important in the systems design and development

Given a good understanding of the problem and a comprehensive description of the customer$/$consumer need $($to include a description of the functions that must be performed $--$ the WHAT, WHERE, and WHEN$),$ this is accomplished in order to develop an overall technical approach to solving the problem. What "technologies" are available that could lead to problem resolution? Will they be available when required? Are they reasonable candidates for consideration when considering cost and other resource requirements? Given several alternatives, trade$-$offs are conducted and a preferred approach is recommended. If there is no apparent resolution, then a recommendation for further research may be appropriate.

This is critical as it forms the basis for every decision $($design and management$),$ every activity, and all else that occurs subsequently! This systems engineering process commences with this step.

This forms the basis for all subsequent design and development, test and evaluation, production$/$construction$,$ and system maintenance and support activities. Information included should address: operational distribution, mission profiles or operational scenarios,peiformance and related parameters, utilization requirements, effectiveness requirements, operational life cycle, and environmental factors $.$

This constitutes a "before$-$the$-$fact" series of statements and illustrations pertaining to design of the system for supportability. It represents an input to design, whereas a plan is developed as an output based on the analysis of some established design configuration. This should include information pertaining to levels, organizational responsibilities, re$-$pair policies, support elements, effectiveness requirements, and environmental factors $.$