Attention to detail makes for a better experience in any industry. A candy on your pillow at the hotel or a mint with your check at a restaurant makes for a more enjoyable traveling experience. Detectives and law officials know that it is in the details of a crime scene that they find success. Engineers and architects know that the stability of the most enormous structure depends on the integrity of its smallest element.
Why then, should it be any surprise that the integrity and success of your design depends heavily on the attention you give to the details therein? Paying close attention to detail simply makes your design more professional.