It's important, you know? It doesn't matter how cool that poster design is or how creative that brochure is if it's not presented well.
I think I've almost seen it all; stacks of crinkled paper, projects mounted horribly crooked on matte boards and scrap books with food stained projects inside plastic sleeves.
If you have no respect for your own work, why should anyone else?
You might as well show up to the interview wearing greasy overalls and no shoes. You might be a great designer—and a more than worthy hire—but, typically, would you expect to get a job dressed like that?
The same goes for the presentation of your work. It needs to be sharp. it needs great craftsmanship.
And it's not about spending a lot of money on a fancy aluminum case or a box made out of Lucite; there are an unlimited number of creative options—purchased and/or handmade—that you can implement to present your work with the dignity it deserves.
But for God's sake, before you go to that interview or client meeting, take a hard look at how you're presenting your work.
Stacks of wrinkled up, food stained photocopier paper ain't gonna cut it. Not unless your last name is Sagmeister or Chantry anyway.