It's a style, mostly because with modern, electronic managed fuel injected bikes, it's much more difficult to perform mechanical style statements. So, paint, wheels, wide tires, bars ... what we used to call "Gee Gaws" ... stuff that mostly adds weight and is supposed to look pretty. Or just different.
It's partly driven by advertising from small ... or not so small ... shops with CNC equipment and a dozen hours of free time in the CAD/CAM application. Although it's not quite true that "anyone can do it" it's pretty close to that. And some of those people are not designers, which is a skill.
Not really the same thing, but large, narrow wheels (19") have been a popular style amongst American heavyweight bike riders for 60 years. The photo is just a natural extension of that, albeit in my opinion just a clever way to fleece the owner of $2000.00, or more. Here in Canada, fat front tires and wide glide front ends are far more popular, and always have been.
I literally only know one narrow glide bike owner, and he runs a 16" tire. Outside a bar you will see 50 wide glides, most with 16" wheels and fat tires, and one narrow glide. Just a different style of bike.