I had no idea that there were measurements for light! That is pretty cool. There are measurements for just about everything else in the known universe, so I guess it is logical that light can be measured, as well.
I suppose that measuring foot candles is necessary if you are growing plants to make a profit. I always just have a flower bed for my own enjoyment, but if I were planning to sell the seeds and plants, I guess that I might have found out about foot candles.