Rally dash redo

Points to ponder... a larger wire is heavier thus more weight stress on the male contact pins.
Your pic shows that these female terminals were egg shaped to lessen or loosen the fitment and broaden the tolerance. The terminals didn't have to be positioned within thousandths. When these connectors aren't carefully pulled straight away the male pins get damaged anyway. The male to female terminal contact/current path equals only 2 to 4 stands of the wire factory used so they may as well have used a much smaller wire.
If you bought new circuit board(s) from aftermarket you would find their pins about eighth of an inch shorter than OEM so even less contact/current path to OEM females there. I'll assume their shorter pins are to further lessen the fitment. No negative feedback proves there is enough contact/current path.
So bottom line... No advantage to larger wire. Possible disadvantages to heavier wire and/or rounder tighter females. You might not need to pull this connection apart again but the next owner might.