The increase in per unit cost probably would be entirely insignificant and minuscule compared to the revenue they'd lose by not being able to charge predatory prices for storage upgrades. So it would be a secondary or a tertiary concern at best..
There was a whole fiasco with Toyota Camries maybe 15 or so years ago where the brakes would go out. It turned out that Toyota skimped out on thick enough wires or wire insulation and either the wire connecting the brakes to the pedal wore out or the insulation wore out and caused the brake wire to short. They chose the wiring they did to save something like 2 cents a unit (each Camry).
The increase in per unit cost probably would be entirely insignificant and minuscule compared to the revenue they'd lose by not being able to charge predatory prices for storage upgrades. So it would be a secondary or a tertiary concern at best..