Why is it beneficial and often necessary to have a structured design approach to computer program development?

Structured designing is clean. It is hard to imagine computer programming without thinking of it as being structured. Structure or a structured approach is built into the very concept of programming. By adding your own structure, you can, as a programmer, add order, power and usefulness to your program.

Modern programs are complex. The computers that manipulate them are very fast. A small mistake can go far in destroying value ( or maybe the entire human race! ). So be clear, be organised and be simple. Even the most complex tasks and algorithms can be implemented with utmost simplicity if you keep on breaking them down to logical levels.

Good Luck!