Well, I agree with you. Horses are a lot cheaper than cars. The can also last long. You don't have to worry about rising gas prices.
Just imagine the benefits of using horses! You can use the * as a fertilizer (as you have mentioned), you can go to places where no cars can go to, you can travel for days and months and you can be sure that you will not need to carry any spare parts. The *el you will need can be found every where. You just need to rest every so often to recharge your horses!