Same reason I like bikes. I can pull the whole thing apart in a day and understand what every bit does. As soon as you start including electronics you end up with black boxes that no human could ever understand entirely.
I'm not sure if wireless shifting will ever become standard. I have an ebike with di2 and I haven't noticed any reason I would want it over regular shifting. You also have the problem that if the battery goes flat you cant shift gears.
One of the big reasons for electronic shifting counter-intuitively applies to “daily riders” more than to race machines, even though at current prices, electronic shifting is rare on affordable bikes.
That reason is that once you have a solenoid, sensors, and a CPU in the mechanism, you have a self-adjusting shifter. The more gears on a derailleur-type system, the tighter the spacing, and the sooner a mechanical shifter needs adjustments or replacement of the cable.
Electronic systems can adjust themselves as needed, offering a massive potential for affordable bicycles to “just work” for people who don’t have the inclination to fiddle with their own adjustments.
The charm of a bicycle being mechanically simple is going away...