There is are two good reasons to favor SOS over WSW, IMO.
(1) WSW doesn’t really tell you who is the better player in any sense. Who cares what side you’re losing as if a loss is a loss? At least SOS is more likely to favor the better player, despite it being out of your control, (while it may seem like WSW is in your control, everyone is trying to win all of their games anyway, so it feels more like an illusion of control attached to something super arbitrary).
(2) The existence of the super bye is a really cool thing in the game, favoring SOS as the tiebreaker makes the super bye better. What good does the bye being “super” help you in the WSW tiebreak? Not a whole lot, considering everyone in contention for a cut generally has a pretty good record anyway. If you, with a super bye, are tied with someone who didn’t have a bye but 2-0d the first round, it doesn’t do anything at all, (assuming you also would have 2-0d the first round). However, it makes a HUGE difference for SOS, not only giving you a round 1 win, which matches you up against better players, on average, than if you had the same record but didn’t sweep the first round, but making your first round “opponent” have a perfect record, which is extremely unlikely for anyone who didn’t have the bye.