It's probably quicker charging the battery and less hassle as well than changing cables. You literally plug the junction box into a socket and walk away and come back. Not to mention even the most active cyclist will only have to charge once a month IF that. Most people can go 3-6 months without charging. I've only charged my battery 3 times in 4000 miles of riding and I shift quite frequently.

Most of the people saying "man I'll never need it or want it" are people who have never had the pleasure of getting on a electronic groupset. The difference is literally night and day.