Transportation Secretary Elaine Chao described this as a "safety" measure that addressed the "unique challenges" or carrying lithium-ion batteries. The FAA has been pushing airlines to reconsider carrying batteries due to the potential fire risk, and the ban theoretically reduces the chance that an incident will put travelers in danger.
The cargo ban will mainly affect people who order batteries. You'll likely find your orders, but they may have to wait for dedicated cargo flights. The battery charge requirement may be another matter. It could mark up to the days of receiving phones and other gadgets with near-full charges ̵