Some years ago Corporate Design should only look nice. Designers has been responsible just for these good looking aspects; people who used to have learned that.
But: Aesthetics are not sufficient nowadays.
A company has targets which differ from those of museums or personal vcards. They are in competition. Decision makers are responsible for profits and success. Design must show its functional capabilities in these surroundings.
Corporate Design must structurize the brand system. It must show the advantages of the company wearing it. It should motivate employees and strengthen the corporate brand.
It should generate pride and work as a guide which shows the uniqueness of the company in competition.
In short: Corporate Design should be the sensual side of the corporate myth.