As you may have noticed, animals trained to haul things are quite lazy and only haul from time to time. The Hardworking animals Mod makes your animals haul a lot more often.
In addition, the hauling skill now requires 9 levels to be learned instead of vanilla 7 for balancing purposes. It will certainly take more time to train animals, but it will finally repay with increased effectiveness.
Having hauling animals is more profitable, and now they can serve as a real work force.