Let's try this another way. What is your reason for the quick-change? How often will you need to do it? In how much time must the quick-change be completed?
If you need to do it once in a while it might be ok. If you need to do it very often the Varg is probably not the bike for you.
I think it is important to have the spare battery option available to those who want it. What good is a $13K bike if it can only be used for 30 minutes and then it has to be charged for 1.5 hours?
Sometimes 1.5 hours is not available. Other times, people may not want to haul around a large, noisy and smelly 240V generator, which is not very sexy, convenient, or neighbor friendly.
Racers and racing teams who want to win races are are willing to pay a lot of money for a spare battery in order to be competitive. It just has to be cheaper than buying a spare bike just for its battery.
I have been working on adding lithium batteries to my van, first 6 kWh, then 14 kWh, and a 4 kW inverter to charge the Alta at the track without making noise. That cost me about than $6K. Bringing an entire extra bike is simpler but costs twice the money, and then I need to wash two dirty bikes af the end of the day. A spare battery that is easy to replace is a much more cheap and elegant solution.
If a spare filly battery can be installed by 1 person with an impact gun in 3-4 minutes, I am sure many people will want it.
Just need a special jack stand to hold and lower/raise the battery while somethins else is holding the bike. That whole contraption will definitely be easier to bring to the track than a 4000-6000 kW generator.