In battery design, there's always an energy - safety trade-off. The proper role of racing regulations is to prevent a race to the bottom in safety. So I'm in favor of standardizing the battery.
If I've gathered anything from "innovation" in F1/FE, it's because of heavy-handed regulations forcing the teams to innovate. Just enrol bankrupting fines/disqualification for battery fires/injuries/death (if they don't already) and we'll see innovation there that can trickle into mainstream.