The method I use to fold my dobok can be seen here:
http://www.mstartkd.com/enc10.shtml about 2/3 of the way down the page (I usually skip the part where you tie the belt around it, but I have done that). This is actually kind of an "updated" method of tying the dobok. An earlier one can be found in the 1972 textbook Gen. Choi wrote. I used that method before the encyclopedia came out.
As for whether or not it's important, it is insofar as it helps keep my uniform unwrinkled. It also helps to conserve space in my bag since I also have sparring gear, tape, a water bottle, etc. to carry. After the uniforms are washed I fold them all, stack them in my closet, and grab a new one for my bag whenever I go to a class.
Pax,
Chris