I think part of it is based off the fact that these soycucks are emotionally stunted people. They are emotionally, psychologically, and developmentally children due to the conditioning and abuse of the Social Justice Racket. Not too different from how a child who is sexually assaulted or raped as a child has a significantly stunted psychological or sexual development from the rape.

They all end up having a horrible kind of "Peter Pan" syndrome where they really need to learn how to grow up, but never have, and are actually conditioned not to. This infantilization can express itself in a whole litany of deviant or pathological behaviors, but a pretty common one is to obsess over youth and childhood.

While Nintendo platform games aren't strictly for children, Nintendo heavily leans into franchises aimed at children and tweens (Zelda, Mario, Starfox, etc). This is where the soyboys tend to demonstrate emotional incontinence as a replacement for "child-like wonder". This is why they virtue-signal the over-exaggerated "soyface".

I would also argue that these same soyboys and SJWs have had such a stunted development that they actually haven't necessarily learned all the basic emotional and psychological lessons towards growing up and socialization that childhood cartoons and figures are primarily designed for. If they are exposed to basic developmental lessons in "Children's Programming" that they have never learned, it can be quite useful and important for them. This is why they might try to focus on it: because they might subconsciously understand that they missed some developmental step.