Based on the following quote...I think that the engineering design process is important to use because...
"Engineers do not always follow the engineering design process steps in order, one after another. It is very common to design something, test it, find a problem, and then go back to an earlier step to make a modification or change to your design. This way of working is called iteration, and it is likely that your process will do the same!" (http://www.sciencebuddies.org/engineering-design-process/engineering-design-process-steps.shtml)