The best film costume of all time? Really?

In Style magazine and British TV channel Sky Movies have conducted a poll asking, "What are the best film costumes of all time?" The winner is a striking green dress worn by Keira Knightley in 2007's Atonement (pictured above).

Now, it's a stunning gown, and one that effectively captures the eye. But looking at the rest of the list, I have to ask if it's a bit early to decide that that is the best film costume of all time. Let's take a loot at the rest of the selections:

In second place is the dress Marilyn Monroe wore while standing over a subway grate in The Seven Year Itch:

In third place was the little black dress worn by Audrey Hepburn in Breakfast at Tiffany's:

Fourth place went to the outfit sported by Olivia Newton-John in the closing number of Grease:

The rest of the list includes the ensemble Kate Winslet wore when Leonardo DiCaprio took her "flying" over the bow, Diane Keaton's outfit in Annie Hall, the glittery number that Nicole Kidman sang "Diamonds Are A Girl's Best Friend" in Moulin Rouge, Liza Minelli's Cabaret costume, Cate Blanchett gown from Elizabeth: The Golden Age and Vivien Leigh's Gone with the Wind dresses:

See what I mean? Every other costume on this list has had a few years (or decades) to establish itself. Additionally, these are all films that have made a strong impact on the pop culture landscape, so these costumes bring to mind the associated effects those films have had on our culture. Most of these costumes are iconic enough that there's money to be made in selling merchandise inspired by them.

Atonement, meanwhile, arrived in theatres a month ago and hasn't received a wide release yet in the States. So far, it just hasn't had the chance to make that kind of impact, and there hasn't been the time to see if that impact will last. Doesn't it seem a bit much to declare it greater than some of these costumes, which have had the chance to prove their ability to endure? I'm certainly curious as to who the respondents of this survey might have been.

What do you think? Is Knightley's Atonement dress so great a costume it towers over the others on the list? Are there any great costumes that belong on the list that are missing?