Cinema "should" not play the role of shaping ethos unless it's just propaganda cinema. If it's art cinema, it simply tell something the artists wants to share. Granted, in reality there might some blending of the two, but regardless, cinema has no "should", just like a drawing has no "should"

On the other hand, these is just likely a trend that will pass... to resurface again some time later, like other type of stories come and go

And on another hand, while it's likely to be taken as an exception, Goku does have that sort of non seriousness nad comedic relief (partly because Akira Toriyama did not like too much drama), yet, despite not looking to be a hero like US superheroes, remains one of the greatests