While both are similar, the differences are still real and we need to practice both processes. We'll assert that we use both processes in "real life" all of the time. A physician, for instance, will use both processes interactively as she forms hypotheses that try to determine what might be causing her patient's ailments. She will turn around and use the design process to build a course of treatment that meets certain success criteria. A scientist may be deep into hypothesis generation but he will eventually need to use a design process for building an experiment that will, within certain definable success criteria, help him answer a question.
The two processes are interconnected in real world application (though they are separate they are both needed in order to fully have a well rounded experiment such as in the scientist example or to fully assess and help a patient such as in the physician example).