Nostalgia. It's one of many ways to stay connected with the past. It was a different time, and most people think they would prefer to live in a snapshot of that era indefinitely.
How many face to face interactions do we have nowdays? How many meaningful discussions? That sort of thing has turned into forums and instant messaging and texting. It's become a rare event to sit with a close friend and spend quality, meaningful time.
So we hearken back to fond memories of those days with vintage pens, vintage cars, vintage watches, vintage clothing... heck some even go so far as to personalize it in their body. I understand TwoTone has vintage KNEES.