Why do companies do this? Well glycerin is a profitable ingredient for the manufacturer. They remove it from the soap and in turn sell it or use it in their own lotion products. You will need this lotion as your skin is so parched from using their "soap". Double profit! The chemicals they add to their products are cheap.
Another side to all that so called "soap" is the chemicals they contain. Antibacterial soap is the worst as it contains a chemical called Triclosan. Triclosan is known to cause cancer. Also parabens, another nasty ingredient. Parabens have been known to cause cancer also. Phthalates is another goody in store bought soaps. Phthalates are known to cause reproduction issues in both humans and animals.
Do you really want to place your health and the health of your family in jeopardy to save some money? The big manufacturers are hoping you do. !