Purpose of sensory detail:
Sensory Details are incorporated in any literary piece or an effective narration to capture the interest of the reader or the listener. The humans own five senses: sense of taste, smell, sight, touch and hearing.
If the narration gives sensory details, the proximity of the related experience to reality increases. The reader gets involved in the experience along with the narrator which make it more credible. The end result is satisfying both for the reader or listener and the narrator.
For example, a writer while describing a beautiful garden may say:
The lovely garden seemed to be masterwork of the Almighty resplendent with a variety of colourful flowers – yellow, red and black roses, geraniums, chrysanthemums, pink bougainvillea and bright orange marigolds. The overwhelming scent of flowers had saturated the air. It was refreshing and rejuvenating. The grass under the feet was as soft as cotton balls, soothing to the feet and the spirit. Humming bees were flitting and fluttering, mesmerizing with their enchanting buzzing.
Surely, a vision to behold.