Why, unless you have a particular situation? You have to preset the water temperature, and that is the temperature you have to live with regardless of what you are doing. Get a drink? Warm water. Wash your hands? Warm water. Wash your hair? Warm water. Need hot water? Sorry, not available. Need cold water? Also not available.
The other drawback of hand free faucets.....unless you have a pumped recir system close to that faucet, you will get mainly cold water out of the faucet.
The problem with the hands free is that unless you set a very long run time, they do NOT run long enough to get hot water. You have to keep waving your hands under there.