It Was
For most of its history jersey was a respectable quiet fabric. It was used on garments worn close to the body and was rarely seen. Then Coco Chanel got a hold of it and blew the whole thing up. She had the brilliant and shocking idea to use it for outerwear too--oh the horror. She liked its stretch and flexibility which lent themselves well to her simple draped style. And it was cheap too. Designers still like it-- especially those whose signature approaches are casual streamlined elegance.
It Became
The white t-shirt boils down these traits into one elegant "form follows function" statement . As it was a cheap fabric that could be put through the wringer it was worn by- and became associated with--the "working-man." miners, dockworker and greasers. Since then it has had aura of rebellious individuality. In the mid 90s Sharon wore a t-shirt (albeit a black one) to the Oscars and caused media uproar. But even before that it has been incorporated into the signature style of almost every new look since the 50's.
Because of the white-t's checkered past (it was seen with all sorts of unsavory characters) it has evolved into a paradoxical fusion of fashion vs. anti-fashion, and is a staple of the modern uber casual or "effortless" dress.
The strength of the look is its straight-forwardness. The lack of adornment emphasizes the wearer. The crisp white canvas frames the face making it the focal point. That's why it can be seen everywhere, from discount bins at Wal-Mart to the runways as part of Haute couture collections
It Will Be
Now, that the basic t with either a v neck or crew can be worn anywhere, the more fashion forward are going for looser, more dramatic cuts. This can be seen as either a push against the more tailored look that dominated since the mid aughties (think American Apparel) or a pull towards the new romantic looks of mid eighties (think Isseye Miyake).
