I disagree. LEGO train operators that do big show often lament the use of batteries. There biggest complaint is the need to constantly be changing and chargin batteries. I think going to all batteries all the time would be a mistake. just my opinion
It would be trivial to add a charging circuit that uses track voltage on certain parts of a layout (to avoid issues with reversing loops on 2-rail setups) to intermittently charge the batteries. I think two unit lash-ups would work well here. One locomotive with sounds, wireless/command, and motors; the other with motors and battery. Steamers could do battery in tender.