ولأن نيل الشيء بعد طلبه ألذ
Because attaining something after seeking it can be more delightful.
This expresses a possible aesthetic advantage of a remote simile. The hearer seeks the connection; when a subtle but fitting relation becomes clear, the act of discovery adds pleasure. Difficulty alone, however, is not a sign of excellence.
A forced or incoherent resemblance does not become good rhetoric simply because it is unusual. The association disclosed by reflection must be precise, coherent, and suited to the communicative purpose.