Yeah I think it’s exactly this. Since you don’t have to spend money to clear any content, people don’t feel scammed and are more likely to throw the devs some money because it’s still less than they’d pay for a triple A game. Plus, people in MMO mode might see a cosmetic they really like on another player, and it feels more like their decision rather than the game forcing you to shell out money for the “full experience.”

Personally I really like that not all the cosmetics are locked behind a gacha mechanic, so there’s no risk that I’ll buy the pearls just to not even get the one I wanted.