Part of what makes Jackson's story so powerful is the manner in which she describes the setting and the lead up to the stoning of Tessie. Jackson does not stray from describing a setting where all is normal. The children playing, the adults talking, the sun shining, and the presentation of life as completely normal accomplishes some thematic connections. The first is that the normalcy of life in the village only brings to light how desensitized the villagers are to their own actions: "This seemingly normal and happy setting contrasts greatly with the brutal reality of the lottery." In this description, Jackson is able to hold use the social setting as a mirror to the condition of the reader, who is able to comprehend that social cruelty happens with an almost frequent and normal pace. Additionally, the third person narration element contributes to a realism that only heightens the cruelty that will meet Tessie. The narration helps to bring understanding to the reader, but it is one that renders the reader as helpless. The reader understands through this detached observation what is happening and, eventually, what will happen to Tessie. Yet, as the people in the village refuse to do anything, the narration creates the reader as incapable of doing anything. In this, the author wishes to use detailed description and full third person form to ensure that the reader grasps what it means to be helpless in the face of intense social brutality, hoping to allow the reader to change, in their own world, what is into what should be.
I actually feel that there is a lot of detailed description in this story, but I suppose your question is refering to the way in which the fate of Tessie and the nature of the lottery is not described in detail and just happens, which of course heightens the element of shock in the story.
Jackson's style is one of evasion and surprise, as she almost ambushes us with the last few paragraphs that make clear the inhumanity of these group of villagers. I normally read out this story to my Senior students each year, and it is fascinating to watch their responses as they gradually get bored about this story they think is about some kind of village celebration, and then get shocked and ask me to repeat bits when I get to the end because they can't believe it ended so suddenly and so horrifically.
And yet, Jackson deliberately uses this strategy to emphasise the way in which such communal violence and strict adherence to traditions, even when it goes against our own values and judgement, is a feature of all of our lives, no matter where and when we live. Violence and murder are presented as simmering only a short way beneath the polite and civilised exterior that make up humanity, and the way in which this village meeting turns from one thing into something completely different so rapidly only highlights this fact, as we are left with the image of Tessie Hutchinson screaming "It isn't far, it isn't right" as her friends and family descend upon her.