As I recall I bought my stainless steel cooker at the Sportsman's Show and it came with a strainer. Since I clean first then boil I also use tongs and avoid having the problem of cleaning the strainer with all of its holes. That said, if your method is to steam then having that strainer or an alternative method of keeping the crab out of the water is a must.

Edit: I am also able to immediately put cooked crab into large stainless bowls and right into the dedicated crab/bait frig to cool it off. Others use the basket to dip the hot crab into cold water to stop the cooking process.