There are limits on everything: acceleration, maximal speed and even noise. Formula E will be boring same way as Formula 1. Identical cars circling around the track.
It seems your data on F-1 are slightly out of date. Yes, the rules are the same for everyone, but each team optimizes within them differently. As for identical cars, I guess McLaren only wish they had a car like Mercedes or Ferrari (or any old car that could actually last an entire race).
There is no longer awe associated with breaking records/introducing diverse tech into motorsports anymore. I guess previous generations had it better as they could watch how somebody breaks 190, 200, 210, ... mph barrier, run engines with 900, 1000, 1100hp for the first time, run two sets of rear or front wheels etc. None of that applies now, motorsports are now regulated and consolidated. New revival attempts introduce super ugly cars (look at IndyCars in the past 10 years, or even current Formula E), all mind-blowing racing that deviates from the norm is now banned (Zanardi's "The Pass" can't happen anymore), engines can't be pushed to higher hp unless we want to allow multiple casualties per race, as Firestone Firehawk 600 shown us in 2001 we already crossed the threshold of what humans can withstand and had to backtrack... F1 is now boring (who cares that some German guy in a red car wins?) and mainly a world unto itself with very little connection to the real world as the rules are a result of decades of political fights (i.e. they aren't representing technological pinnacle of what is possible rather what powerful people allowed each other). There were glimmers of interesting things happening with drifting etc. but they never had mainstream potential. I really don't see much future in this, the existing motorsports can be probably milked for a while with a proper marketing strategy, but the future lies elsewhere.
It would be interesting to do remote control. I.e. nobody in the car. Two classes: one with restrictions (i.e. driver must be in control - no assists / etc. May be tricky to define.), one without (want to go fully computer-controlled? Sure!).
Although it would be interesting to go "you must have a space where a person can fit, and if you ever kill the dummy inside you lose the race" (defined a little more precisely, of course).
Remember: you probably want to keep the scale vaguely car-size. That way you'll get the most applicable innovation coming out of it. And also that way it'll tend to be the most interesting to spectators.
Formula E is actually worse than Formula 1, since they are built by the same manufacturer. You can't level the same criticism at F1 these days, with a dominant team like Mercedes.
Renault's monopoly is temporary - it's to bootstrap the series. I think they should replace F1's every-constructor-makes-their-own-chassis rule with a rule to have everyone build their own powerplants / drives. That's where you want this series to provide innovation.
If you think formula 1 cars are identical, you're not really paying attention.
They look the same in the way a Lenovo and an Apple look the same.
There are rules on track and wheelbase, crash structure and aero wing size that tend to dictate the overall silhouette, but from there, everything else is very different.
Identical cars make for better, more exciting racing. It comes down to driver skill instead of who can invest the most money. That said, I think restrictions like F1 are better because they lead to interesting innovations.
