A simple modification as in effect on weight and balance - nil , effect of electrical loading - nil , expensive parts required - no
Very often on most main wire looms manufacturers do indeed add spare wires , for the purpose of repairing damaged wires in a long run between connectors in awkward places - on the wiring diagrams hook up lists these are marked as "spare"
I guess after 35 years wiring up aircraft , I consider such a mod as easy compared to some I've installed as its only 3 wires at a maximum instead of the usual 500 or so and a few dozen relays and a whole host of hardware and stripping down the flight deck and E and E bay and pressure bulkheads and ( you get the picture I guess)
Ever seen an IFE fit/instal ? That's just to entertain the punters , fair bit in that too