A direct statement might say “Fulān karīm” — so-and-so is generous. The allusive form “Fulān jabān al-kalb” — his dog is timid — can communicate the same virtue while also presenting a recognizable sign of it.
The indirect form may be stronger because the listener infers the trait from its imagined or conventional effect rather than merely receiving the label. This advantage depends on the listener's understanding of the association; an unfamiliar sign may obstruct comprehension.
Kināyah is not automatically better than explicit speech. Its force comes from an appropriate occasion and a sufficiently recognizable link.