One of the main contributors to sliding door popularity is a change to the 2009 IBC code for corridor doors (doors that open into a corridor and are installed parallel to it, not those that divide up a corridor or hallway and are installed perpedicularly). For a long time, corridor doors were required to be fire-rated, but the 2009 IBC changed this to non-fire rated, or smoke-rated only. This meant that sliding doors were now appropriate for use as corridor doors.
Hospitals quickly adapted to this new code, as sliding doors are easy to use by patients with mobility or grasping/manipulation issues, as well as by employees whose arms might be full of supplies or patients!
Sliding doors are also gaining popularity because they take up so little space in walkways, expecially in small living spaces where square footage is at a premium. As world population grows, making the most of livable space has become a huge design concern. Sliding doors help make the most of floor space and also have that sleek, modern look that is so popular.
On the other hand, rustic design is also gaining traction, and sliding doors - especially barn door hardware - is fitting into that niche perfectly. Barn door hardware certainly has the look of a simpler time, when solid hardware was necessary. It is a design style sliding doors also fit into.
CBA manufacturer Hager companies has created a few lines of barn door hardware to fit any design style.
CBA manufacturer Western Integrated Materials also has a line of sliding doors. The Aluma-Glide system takes it one step further - it places the entire sliding assembly within the space of the wall.