I think, it's partly that seriousness, the forces of seriousness, of humorlessness, would limit us to narrow thinking, rigid ideology, cruelty, and a tunnel vision whereas humor obliges us to have an open mind.
Mislim dijelom zato jer ozbiljnost, jer bi nas sile ozbiljnosti, neduhovitosti, ograničile na uskogrudno razmišljanje, krute ideologije, okrutnost i suženi fokus, dok nas humor obvezuje da budemo širokih nazora,