I always want my bike lighter but accomplishing that you have to start making some real trade offs, in this case it will be hard to make it very light considering the bike already weights around 37.5lbs without any ebike parts on it. Still though that is a small fraction of what even the lightest (and still capable) dirt bikes weight. I expect if you wanted the a very light bike with still plenty of power it would be something along the lines of a carbon trail bike with a two stage belt or chain reduction similar to the Lightning rods but with a much lighter brushless outrunner aggressively air cooled and using a modified rear cassette and derailleur to take the power.
For another reference point I just finished a friend's build of a Nomad 2 in carbon fiber with a CYC X1 stealth and it certainly has more power than it needs, combined with it's short wheel base (size small frame) and light riders using anywhere near full power while keeping traction in the front end is tricky. I haven't weighted the bike but it's pretty light for what it's got, although currently has a very small backpack battery. Like the example above if I took that same setup and removed the gearbox from the drive, improved motor cooling (forced air) and increased current a tad, then sized the chainring down much smaller to make up the reduction it would be lighter with similar or more performance (especially if you added some of that weight from the gearbox into the motor size) but you would have to give up the ability to pedal.
I think there is a place for electric motorcycles that are slightly smaller and lighter than most motorcycles but again they have to be designed to be good at certain things and not good at everything. I've always found motorcycles uncomfortable and unsatisfying compared to bikes, which probably explains the DR350 that has been sitting in my garage for years unridden. I think this is partially down to me, a 200lb+ guy on that DR350 can maneuver it's weight and control it, the reach and height are comfortable, for me I can only barely tip toe even with the suspension slammed and my 120lb mass has barely any effect on the bike and I feel like a child sitting on it. Sure there are smaller bikes but very few seem to really be where I want to be. Those factors combined with I find EVs super interesting to build and work on and find gasoline engines and drive systems unnecessarily complex and inefficient.
I would someday like to build a street electric bike for 50-60mph speeds but I think it needs to be designed a bit different than the current crop of available bikes to be better than a gas bike for what I'm after. For one I think you need some serious aero work to have any hope of good range and reasonable weight. Starting with one of the few small bike frames in the 50-125cc range and giving it a realistic range and stupid torque through ludicrous phase amps.
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