Relax, the next set of regulations will surely consist on some kind of Hybrid system (mild or not), before going all electric.

Regarding the sound, it is a known problem by manufacteurs and there are some very good engineers working to solve that, Mclaren for example has completely dismissed an all electric car for the foreseeable future until they find a solution to make it sound as exciting as there other models (even if they already have an all electric mule running).

Regarding the popularity of electric car racing, I think the low volume of engagement of the Fomrula E page of this forum is pretty self explanatory.