The message is the oxygen - it is the life of your materials. If done right, it can truly take on an organic quality creating a responses and ultimately generating revenue. It is the most important piece. Without a great message your materials will be stale and lifeless.
The design and quality of the print is the body and outer attire - it is the appearance of your materials. Just think about the job interview process - 2 candidates with the exact same skill level walk in - one is dressed professional, has on the right attire to fit the company they've applied for, and looks like they would fit in? Chances are the candidate that looks the part - gets the part.