Shit I remember when I was a kid briefcases were all the rage. It's just what men carried to work. I couldn't wait to get my first briefcase, and when I did, it was a Samsonite, and I loved that thing.
They have not disappeared by any means, but they are a far smaller men's office work carry than they used to be. And the people that were traditional as things changed were also probably aghast at these newfangled more casual bags coming into the office, and used their own version of 'hipster' to criticize them. Things evolve. It's normal.