It turns out that it is the sound that is actually the most important to the bees. If you remove the wings of the dancing forager, it does not communicate distance to recruits. Remember, it is dark in the hive, so vision probably plays no role. Also, the potential recruits don't see the dance from overhead the way we diagram it. They attend from the side.
Recent work shows that the dance conveys distance information quite accurately.
The energy expended during the outward flight of the forager determines the dance. Greater distances, the slower the rate of dancing. Headwinds require more effort to get to the source, therefore the bees dance slower. Tail winds, just the opposite. If you add weights to the forager, it will dance slower for a given distance.