In Keroro Gunso why does Kururu wear a diaper and suck on a binky in most of the opening and ending sequences?

In "Keroro Gunso," Kururu wears a diaper and sucks on a binky as part of his quirky and comedic character design. This portrayal emphasizes his childlike and mischievous personality, contrasting with the more serious aspects of the show's plot. The absurdity of his appearance adds to the show's humor and lighthearted tone, making him a memorable character among the cast.