It's a good idea for a student of graphic design to learn how to draw. Sure, you can bypass this and do everything by computer, but drawing by hand trains your mind and your eye to seek out details and improve your grasp of visual forms. It develops different parts of your mind that relate to composition, color, anatomy, depth and mood, and helps you directly perceive things and interpret them.
Much of what we relate to in our lives is linear. For effective visual communication you need to develop a nonlinear, direct connection to the actual tensions, feelings, and dimesions you are interpreting and expressing in your work. Drawing can be an invaluable way to develop a direct connection to the world around you and develop your own outlook.
The ultimate aim of the graphic designer is to understand, use and coordinate the tools of the craft (typeface, art, photography, printing, etc.) and create a message that rises above them. As in music, you do not pay attention to the instruments alone but to the composition as a whole.
Draw some architecture, some life studies, and some abstract compositions. Start with basic media like pencil and charcoal, and then try some things in color. Look at master drawings for ideas and inspiration.
In interpreting three dimensions on a flat surface with a defined page shape, you encounter a number of issues. Evaluate how light falls across an object and how you can make shapes out of shadows. Shading, the gradation of darkness, is one of the most important factors when you draw an object. Shading and defining basic forms can provide a truer understanding of a dimensional object on a flat surface, and can make the difference between a really shoddy piece and a proper drawing. Get beyond outlining in your definition of form.
Appreciate your overall use of the page. Be familiar with positive and negative space (negative space is that space that falls between the objects) and understand they are all part of the overall composition.
To be successful at graphic design you need to develop a taste for solving visual problems and a set of strategies for resolving them.