Oh, I see what you mean about going all-electric. I think there are other reasons why they can't do that. Formula E cars would be completely unable to complete anything like an F1 race. We'd need some revolutionary new storage tech for that to happen.

I'm of the opinion that the fuel flow limit was a bad idea from the start. Fuel efficiency is a worthy engineering goal even if its relevance to "sustainability" is pretty negligable, but restricting the total amount used and basically anything else makes more sense to me rather than constraining the instantaneous fuel flow rate. But I suppose it's seen as a cost-cutting measure: Low-revving engines are less likely to blow up.