One reason to learn how to toilet train your cat is to avoid exposure to potentially dangerous chemicals and ingredients in cat litter. A lot of litters contain perfumes and colorants that may be harmful to your cat. Even if they are "natural" they could cause problems.
There are arguments against clumping litters and whether or not they pose a risk to your cat. The thought is that the litter is dangerous if it gets into a cat's stomach and starts to swell or clump. There is still a debate about how much of a risk this really is, but the theory has some merit. If you have dogs in the house as well, this really could be an issue. This is pretty gross, but it could also be a problem if you have small children at home.
Some natural clay litters contain silicon, which is listed as a carcinogen by the California EPA. The dust can get into lungs and cause problems. Even though the clay is natural, this litter could pose a health risk to you and your cat.
Another reason to learn how to toilet train your cat is to avoid bacteria build-up in the litter box. This is a concern for your cat as well as you and your family. Cat litter should be changed every 4-6 weeks to prevent bacteria from growing. If you're diligent about changing the litter AND washing out the litter box that often, you should be okay. Please note that you do have to wash out the litter box with soap and water to kill any potential bacteria. Toilet training your cat is more hygienic in this respect.
