Why are names important?

The author wanted to create the impression of a large gathering of people. She does this by using the word "crowd" repeatedly throughout the story. For example:
The crowd was quiet. A girl whispered, "I hope it's not Nancy," and the sound of the whisper reached the edges of the crowd.
Jackson also names many names in order to enhance the idea of a crowd. Some of the names are used with variations. For instance, Mr. Summers is also called Joe, and Mrs. Hutchinson is also called Tessie and Tessie Hutchinson. Here is a list of all the names mentioned in the story in order of naming:
Bobby Martin
Harry Jones
Dickie Delacroix
Mr. Martin
Baxter Martin
Joe Summers
Harry Graves
Old Man Warner
Tessie Hutchinson
Mrs. Delacroix
Clyde Dunbar
Mrs. Dunbar
Horace Dunbar
Jack Watson
Steve Adams
Allen Anderson
Bentham Clark
Mr. Delacroix
Harburt
Bill Hutchinson
Jones
Mrs. Adams
Overdyke
Percy
Don
Eva
Bill Hutchinson, Jr.
Nancy Hutchinson
Nancy Hutchinson’s unnamed school girlfriends
Dave Hutchinson
Mrs. Graves
Clyde Dunbar is not present because he is home with a broken leg. But the questions and answers about him help to show that attendance at this ritual is compulsory unless someone has a valid excuse. In other words, it shows that everyone else is present. They can't escape by staying away. Mrs. Dunbar draws for her household in place of her husband.

When Tessie Hutchinson is selected as this year's victim, Old Man Warner helps to create the impression of the entire mass of about three hundred villagers converging on her with stones. He says: "Come on, come on, everyone."

Steve Adams was in front of the crowd of villagers. It is interesting that Steve Adams had just been hinting to Old Man Warner that it might be possible to give up this annual lottery.
"They do say," Mr. Adams said to Old Man Warner, who stood next to him, "that over in the north village they're talking of giving up the lottery."
Yet Steve Adams is joining Old Man Warner in leading the crowd of Tessie's friends, neighbors and relatives all armed with stones.