Steinbeck decided to name his book after where it takes place, so it doesn't take Sherlock Holmes to figure out that the setting is a pretty important part of the book. Unlike, say, Robocop, it's hard to imagine Cannery Row in some other place. If Doc and Mack the boys and everyone were in New York, how would anything that happens in the book be possible? There wouldn't be a Palace Flophouse available, Doc would never be able to find all the sea life he needs in the Hudson River and Lee Chong sure couldn't be the only grocer in town.
The buildings in Cannery Row—the whorehouse, the Malloy's boiler, the Palace Flophouse—aren't just places; they're characters in the story.
Steinbeck's descriptions of Cannery Row emphasize its heterogeneity: it's a big mix of classes, races, ages, and sexes.