If the receiving team scores a TD and makes the extra point, the worst that can realistically happen is that they are either tied in a game where the next score wins or they have to stop a 2 pointer. If the opponent scores and opts to kick for 1, then the receiving team has the advantage. If they score a FG and can hold the other team to a FG they gain a huge advantage. The only advantage for the kicking team is knowing what they have to do and possibly having 4 downs. SF failed in the game, but the rules are pretty even between kicking and receiving, maybe slightly favoring receiving.
SF can blame their loss on being outcoached several times in or near the red zone.
It also changes what they might have called in third down.
And that is an absolutely huge reason.