Hm, some decades back it was fashionable to smear fat on a lens for a certain dreamy look - maybe you should try that with a cheap filter?
Joking aside I know what you mean, that's why I sometimes love to use vintage lenses.
I might be wrong in assuming that you might refer to a head shot taken at F1.2. If yes, below is my answer, if not; my apologies.
It is not about a cheap filter look; it is about having options when you need it.
Many assume that if I buy a 1.2 lens, I could use it only at F1.2
Reminder:
1 - depth of field is a function of distance. If people have been using it for a head shot at f1.2; that is their choice. I use my F1.2 when a full length person occupies 1/3rd of the screen. At that distance a dof of a 50mm 1.2 is deep enough. Believe it or not but under moon light, only that f-stop can save you from smear fat from a too high ISO without blurred movement.
2 - An f1.2 lens is a lot sharper at F1.8. Not because you bought an F1.2 that you will be shooting all the time at F1.2. In fact, I have Sirui F1.2 and I use it most of the time at F1.6. Finally, it is now time to be able to shoot with an auto-focus.
3 - having an F1.2 gives you chance to have that amount of light when needed, compared to not having it at all; cheap or expensive filter look.
4 - There are many things out there that don't care much about what is your dof. Flat surfaces for example; you can shoot them wide-open and dof is plenty enough.
Now, combine all four options and see if the lens might be useful to many photographers. I am sure that others have found other ways to use such a lens too.
Looking at an F1.2, or even F0.95 lens, I pay attention to sharpness, chromatic aberration, but mostly proneness to flare against the sun; then I decide if it is worth or not.
Having an F1.2 is about choices; compared to not having it at all. I wish Canon does the same thing at 20mm for example, without spending 2K.
