A Few years ago when the Lightning was at Laguna Seca, I asked them about a transmission.
He said that he could roll the throttle at 150 mph and bring up the front wheel. Why would
he want one.
He wouldn't, for 1 reason: They have a Remy HVH 250 motor, a high power Rinehart controller and high power battery.
Its the same reason Brammo has a fixed ratio on their race bike, the motor and battery pack are powerful enough.
If you had a gas engine, such that it could go from 0-150mph in one gear (of course you'd still retain a clutch) and remain in its power band most of the time, you wouldn't think it'd need a transmission either. My buddy's R1 can do 90 in first. Does he need a transmission? With your reasoning, maybe he doesn't. So why does it need one?
I recall that the reason that Brammo chose the Transmission is so they could gain some performance (with the same motor) by adding a transmission because you can put the motor into its power band whenever you want. Motors have an HP curve, so on either end your HP falls off. With a transmission, you can peak your HP in every gear. You could be fast off the line, and also get to 110MPH quickly. With one ratio, you could gear for 110, but have slower acceleration at low speeds. As another benefit, you can help offset the loss in efficiency due to transmission by changing gears so you stay in the "happy place". With one ratio, you're stuck with lower efficiency at RPM's outside of the efficiency curve of the motor being used.
I'd be fine with or without a transmission. I would appreciate the simplicity I'm sure, but I do also enjoy the transmission performance/efficiency benefits above. I do like to keep at 4K RPM at my cruising speeds, whether its 25, 45 or 60mph, to try and get the highest efficiency out of it. I did an unofficial test once. After a full charge, I ran the bike until about 95% SOC. In one test, I stuck in 3rd gear and ran the bike. Then I ran for 5 miles along the same route, trying to keep my acceleration similar. I didn't gun it, got to speed with traffic, cruised at the speed limit, etc. Then I did the same, but used 2 through 5 gears like normal. I was able to have 1-2% higher SOC when I returned home over the previous test. Again, not official, and not that much, but its there. But again, I'd be fine with or without. It doesn't really matter a huge amount to me.
For me:
I think the Zero is pretty ugly
I think the quality of the parts have been below what riders expected
I find the number of glitches in the BMS/VCU/Controller to be bothersome
I wanted L2 charging, without having to buy more stuff
I basically had my choice between both of them at a very similar cost (My Brammo was a Press bike), and went with the one that I felt was higher quality, better looking and came with a better charger. If the Zero had those, I'd have gone with a Zero, but it didn't. Transmission never came into my mind when justifying one over the other.