Necessary? No. Extremely helpful in remembering, having control of your dreams? YES. It's the same as Chi and Tai Chi. If you spend an hour a day meditating upon drawing energy from whichever element you choose and storing the energy, that energy wil become your own. Then, when you practice Tai Chi, your abilities will be much more powerful, because it isn't just YOUR Chi, it's the Chi of Earth, Wind, Water or Fire.
Same with Chakra Meditation and dreams. As you clear your chakras, your entire being is more in-tune with existance as a whole. With enough practice, one is able to perform astral projection at will. Able to recall destination, and actions performed while on their journey in full detail. Provided the chakras are balanced and clear.