I think bicycle accessaries are of these things that developed over time past the point where it would have been sensible to rethink how things are done. I think it would make sense the rethink how all those bike attachments are integrated.
A bicycle without any attachments is already nice. It can be used without them and none of the things are necessary all the time. So it can make sense to have them detachable. But probably most people use their bike mainly for one thing - transportation, mountain-biking, sports - and need the same combination of attachments most times the bike is used. (Minus the lights when it's not dark.) I think it's rather peculiar that people buy, attach and use all these extras without questioning the crowded state of their bicycle frame. Let me list the things that I find useful myself.
- Bell (*)
- Front light (*)
- Back light (*)
- Phone/GPS holder
- Phone charger
- Action camera
- Remote for indicators (in helmet or jacket/shirt)
- Horn
(*): required by law when driving on the street
So, in this configuration, when you get back from riding your bike, you have to turn off the front light, turn off the back light, turn off the helmet indicator, turn off the indicator remote, check the charge of the front light, the back light, the phone charger, the GPS, the helmet, the helmet control, the horn and the action cam, detach the things that need charging, bring them in the house and plug them in for charging one after another. You may also have an electronic lock, additional front lights, a breaking light, the remote control for the breaking light and a headlamp. Half of them still have a micro USB port and none of the batteries last for dozens of rides (unless you ride mostly when it isn't dark). Sure, that comes with the benefit of having these devices, people seem to think. But they don't do all of this when they get out of their car. Because it wouldn't make sense to have a separate battery for every electronic device in a modern car. Neither does it make sense on a bike.
It would be nice to have a central battery for everything on my bike and a single on/off switch. But I don't use it enough to see me investing in building it myself. Because if I'd do it, I'd want it to be safe and secure in any weather, look good and not be too clunky or heavy. So I'd have to invest time.