There can be no understating the importance of a good aesthetic. Now, we are aware that looks are not everything. Indeed, looks cannot be the single focus for any one object or idea or aim. However, being the visual beings that we are, we tend to utilize and focus upon our sight more so than any of our tactile or olfactory sensibilities. We are visually oriented, and as such we enjoy things that catch our eye and appeal to our subjective senses of beauty. You must have some substance behind a pretty facade, however. Judging a book by its cover works both ways: if you have a flashy cover and a dismal story, there is only so far to go. If there is a good story but a dismal cover, you could be turned off from reading what could be your all-time favorite tale. We must have an interesting or at the very least engaging aesthetic to go along with our object of substance.
That is why design is so important. No matter if your tools are the simple pen and paper or if they are within the realm of sophisticated software such as Photoshop, design and aesthetic can strike the very heart of the customer or the client. You give them something of substance, something that not only looks good but is of a high standard of professional quality in other aspects, they are more receptive to whatever it is you are offering them. If your product is merely pretty, you might get your foot in the door. Despite what Hollywood will tell you, you cannot get by on looks alone. Have a good idea and a solid plan. Only then should you worry about the color scheme.