I have not studied this topic, but, from what I know, establishing a positive credit history is important simply so you can buy things.
For example, if you bought a foreclosed house and need to remodel it, the bank will grant you a loan Only If you have good credit.
Another example would be when you buy your first car. If you pay in store for the car, you will need a loan. The bank will look at your credit to see if you are capable of paying back the money you borrowed.
A simple thing to gain good credit and trust is to pay bills and send them in on time.
Hope that in some way my answer helped.