Red Door -- NEX-5 & Minolta MC Rokkor 58mm f1.2.
There is something about larger aperture lenses that make people want to have it. Let's face it, for the f1.2 lens, the 1/3 of a stop brighter than the f1.4 lens is not a huge deal to be practically different, but the price is usually two to three times more than the f1.4 lens. I guess there is a certain pride in owning a fast lens that most people would not consider, due to much higher price, so they are less common. And, to some degree, that 1/3 of a stop of light may actually help nail that picture in low light.
Whatever the reason, fast lenses fascinate people. But, for pictures like the above, any 50mm f2.8 or even 50mm f4 lens will do just fine. This kind of picture does not show off the capabilities of fast lenses. They do best in low light and very shallow depth of field type of photography.