You are 100% correct, but as to why they did not do it in the first place, you could also ask why they did not perceive that wiring gets old and resistance goes up, thus causing a higher voltage drop across the same wire. You can also wonder why they chose cheap wiring. either way Ford knows about it and thats why they had a TSB.
You can just run a new wire, but why would you? If FORD already knows the fix.
