If you cut branches off it forces more energy to the tops of the plants and allows more ventilation for the bottom areas, but honestly it's a dumb idea. The bottom branches first of all are the largest branches on the entire plant, so cutting them off is just wasting a ton of growth. The top buds will become more developed and probably slightly more potent, but why waste the bottom nugs, even if they are popcorn-ish. Like veggie said you can just make hash with em. If space is an issue, than it would make sense to chop a few of the bottom ones off, but only so the plants aren't crowding each other as much.