Ethnographic tools give developers guidelines for improving their technology and service. For example on an online banking website, ethnographic tools will observe the details and maintenance of their site, providing thorough analysis of any problem areas as well as an areas that in general could use improvement, just so that a user has a seamless experience trying to use their online banking.
Design is meant to be desirable and beautiful and elegant and appropriate. Almost everything we interact with in our day to day lives is the product of design. A design is never complete until the needs of both form and function are met. An object should meet its purpose, (eg: A chair should hold the weight of a sitting person) while simultaneously making the object easy and comfortable to use while looking aesthetically appealing.
My favorite cereal being Lucky Charms, I can only eat it at certain times or when I’m in the right mood because Lucky Charms has been branded as a fun and enjoyable cereal to eat for kids specifically that are “magically delicious.” By associating the cereal with fun, I tend to want to eat Lucky Charms if I am not quite in a good mood, with the goal that the cereal will cheer me up.