Maybe... It depends. From a sheer physics point of view, less weight makes for better spins and easier inverts. However, some moves require intertia stored in mass for proper completion - like a tantrum. A board too light and you may under rotate, a board too heavy and you may over rotate.
The obvious question is "What is the ideal weight?" That is as individual as the person riding. My boards weigh a lot becuase I need the largest size in both boards and bindings. Several years ago there was a weeght push. Blindside made the Air Cell binding, which was about the lightest ever made. Goode made a carbon board that was about 1/2 the weight of the standard board on the market today.
My opinion is that you buy what works for you. Most boards will be about 6-7 lbs or so. Bindings will continue to be heavy until we get to exoskelatons with inserts. That is a long way off as I see it.