Video link below. The message for me is that this expensive luggage makes you profoundly unhappy. What’s behind the theory that being disaffected and dour will help sell the product. So many unhappy young men.
Runway modelling has been like that for years, maybe decades. The idea is for the model to be attractive, but as blank as possible. They get paid to draw attention to the thing they are modelling; any bit of happiness or expression would draw attention to themselves. The way we make celebrities out of people whose job is to be a coatrack has always perplexed me.
I’ll admit I haven’t seen this before with people modelling luggage, but the principle still holds.
Catwalk shows are not about selling anything (in the sense I think you mean), they’re industry events. The designers are announcing their new styles for the season to store buyers, the press, and other designers. These are all experienced fashion people and they don’t even look at the models unless they screw up - they’re just coat-hangers with legs.
They’re all in bad moods because they can’t eat anything.
They are there to be human hangers. Hangers do not smile. It takes away from the clothes.
I thought it was so you could get an idea of how your teenager would look when you made him wear those clothes.
To me it looks like it goes beyond simply “not smiling”. A lot of them look like they are actively pissed off.
My theory is that the walk, the pissed off look, the ridiculous music, is supposed to be entertainment for those who are dragged there by people who are only into the clothes. 
Sort of how they sneak humor aimed at adults into kids movies so parents watching it with their kids aren’t bored to tears. 
This is a decades old observation, glumly suffering models of both sexes. (Along with ‘what is up with those goofy unwearable getups/why are their genitals hanging out?’ Because: It’s fashion! no more needs be said!) I imagine they thaw out and work up a pleasant enough expression when the rich and famous offer to marry them, or at least rent them for a weekend out on the yacht.
But all the cocaine should balance that out.
It’s not the luggage. Look at those pants. I’d be entertaining thoughts of spree murder if made to wear those pants.
But, seriously: what the prior posters said. They’re supposed to be a blank living coathanger. And many people seem to believe that “neutral expression” means the expression of the death-mask of someone who died of aggravation.
Anna Sui is one of the few who has her models actually look happy to be wearing her clothes.
http://www.zimbio.com/Anna+Sui/articles/9/Models+Anna+Sui+Look+Happy
I’m blanking on her name, but I remember an interview with a Spanish actress who’d previously been a model, and she’d started as a “tryout model” (that is, the clothes would be put on her to see how they fit, not to show to clients). She explained how, when she got promoted to “showcase model” (displaying the clothes to individual customers), she was told to look “as sour and bitter as possible… damnit, this is going to be a problem, you’re such a cheerful girl! OK, try this: when you’re out there, think ‘yeah you’ve got the money and the husband, you bitch, but I have half your age and half your weight!’” This was in the late 60s.
I can see how a distant brooding look could be preferable, but they look like they have either an itchy anus or they’re on there way to the principle’s office.
It’s been a thing for at least sixty years, with modeling generally, and probably for most of the reasons already suggested.
How do I know this? It comes up in the original The Caine Mutiny novel, published around 1953. At one point, a junior officer to Willis Keith begins his tour of duty on the Caine and, as it turns out, is utterly unable to hold up his end of the work aboard ship, because he spends all his time mooning over a newspaper lingerie ad. Said ad features a willowy model with an expression of faint repugnance “as if someone had just offered her a jellyfish to hold.” (Really love this passage; Herman Wouk doesn’t usually come up with these trenchant similes.)
The earlier name for these models was mannequin.
They are three-dimensional stick figures. Facial expressions not wanted.
You’ve gotta see Zoolander.
Lambert Simnel was a baker’s boy, and Perkin Warbeck was a male model. Both pretended to be one of surviving Princes in the Tower, in the employ of nobles who sought to overthrow Henry VII.
A friendly smile is a valuable asset. Simnel was spared, and given a job in Henry’s kitchen. The Warbeck was hanged.