I could dig some electronic shifting. There is a lot of shifting with the 9 spd riding around town, lot of speed change, imagine a 12 spd would be even more. I could see the attraction of higher gear numbers if I was going to maintain a fast pace. Riding the wired ebike which has a 7 spd and that works really well, think if I had to change gear numbers it might be something like an 8 spd, bigger chain, if the gear selection was there. I have adjusted both the 9 and 7 spd gears for better spacing and am happy with them. I did try an 8 spd chain on the 9 spd cassette and it didn't work, well, it did work, but there was noise where the chain would rub the next cog.
I see there is now a 13 spd, that is a lot of gears. I would still try the electronic shifting with fewer gears, probably have to wait for the trickle down effect when they run out of things to change.
The present cable setup has worked well for 6 yrs and almost 4k miles with what should have been only a cable changeout. That's pretty good.