To elaborate, one focus people might use is to make it all about the customer. This is for them, after all, and they're business is going to be the lifeblood of your company. Every decision made is going to be centered on whether or not this will be something the customers like. All commercial printing done will be overshadowed by a desire to keep the customer happy.
The other extreme is a company caring only about what they want to push, or what they need to sell. A new item is coming out and they want it to be big, and so they decide that this is what the customers are going to want to buy. Every ad is emphasized by the language stating to your customers that they need to buy this item, and they want to buy this item, whether they actually do or not.
Good marketing finds a way to combine these two sides of the spectrum to provide an effective give and take between both company and consumer.
The downside to only focusing on the wants and needs of your customers is that you aren't always able to guide the message as much, and you certainly won't be as capable of altering yourself in anyway or releasing new products. After all, you're only giving the customers what they want, but what if they don't realize yet that they want something? Sometimes you have to guide your agenda and help them to realize what benefits a certain type of product can offer them.
This might affect the style of advertising you use as well. How do you tell when one type of advertising works? You get sales after using it. But does that mean this is the only kind of advertising that will work? Do you shun the rest of the world of commercial printing in favor of a single form of advertising simply because it initially had good results?
People like to be surprised, and a company trying as hard as possible to please them isn't going to be as capable of offering up some unique surprises.
Your goal will always be to generate more customers and keep them happy, but that doesn't mean you need to disregard your own needs in the process. Sometimes you need to expand your market into different areas, sometimes you need to alter your brand to keep up with the times, and sometimes you need to get new products and ideas out there. Form a good balance between fulfilling your needs as a company and your customers needs and you'll find the best of both worlds when it comes to your marketing.