Originally Posted by pretbek
I find that also using the rear brake stabilizes the bike when braking.
And like the others said: Learn to use the rear brake too, then practice, practice, practice your emergency braking...before you have an emergency.
Pretty much this.
Without writing a full graduate paper on the subject (I'm sure you will have that before too long), both brakes have their uses so ultimately you want to learn to use all the features of the bike, not just some of them. I can understand telling a new rider to just use the front brake until they become competent with it, there is a lot to learn / co-ordinate when you are starting out but after a week I would expect the new rider to be using all the brakes.
In the same way you would introduce more advanced steering inputs as the riders competency grows, the end result you are aiming for is a rider fully capable of getting the best they can from the motorcycle.
In answer to your brake question, I use the rear all the time on every bike, dirt, road and track, it's a great tool, learn to get the best out of it.