I am a high res and ultra wide lens hound -- but not to shoot ultra narrow DOF shots, which I find appalling when used as a general style.
I wonder how many pros regularly shoot ultra wide open when the subject is fairly to very close. Sure for a special projects or in ultra low light that is fine - but for properly lit every day headshots or portraits -- my guess is NONE.
Real Pros understand that the whole of the face, the whole of the subject and/or the whole of the product had better be in focus when they take the shot otherwise their clients will not pay them.
When taking a portrait the setting is very important to. So shooting with too wide an aperture is simply going to obliterate all that money you invested in hiring a venue, paying a set-builder and staging a scene. Sure subject separation is very important -- but not to the point of obliteration.
The fact one buys an ultra fast lens does not mean one shoots it wide open all the time. AND certainly not when close to the subject.
When shooting from longer distance OK shoot wide open if you wish to from 15ft/4m or more - the face of a normal human subject should be in focus at f/1.2 on a 50mm and a full frame sensor and anything further away than 10"/25cm will be out of focus and so on. I regularly shoot lions before sunrise wide open with a f/2.8 and this is one reason to buy and use these lenses.
For some -- who take photos of subjects 1m away wide open -- they seem to want to say well I invested 3k+ in this lens or more so I have to shoot it wide... well no !! It sounds like they overbought to have a trophy object rather than a tool that they needed to do their job. The category of Dumb A## includes everyone who brings such an attitude to a job.
As I said on occasions completing a project using the widest apertures or using a tilt/shift lens or lensbaby to manage/reduce the DOF across the scene can be good reasons to shoot ultra wide -- but beyond this it is clearly I form of "showing off" -- hey I have this really expensive lens and it can shot f/0.95 -- OK I take crappy photos but look at the "expensive gear" I used, which cost more than your car........ we all know the storey.
So why buy ultra fast primes then -- we those who shoot in low light or astro need the ability to collect as much light as possible with the sharpes settings they can with their cameras -- event, concert and sports shooters are victims of terrible light and need to shoot with crazy gear - like the 200/2.0 I recently sold.
But for the rest of us it is the "promise" of higher edge to edge sharpness and resolving capability, better clarity and transmission and simply a better photographic outcome. These days super primes like my Z 400/2.8TC comes with exceptional AF motors and crazy coatings that take them to another level, way beyond the performance of the previous generation lenses.
Only the photographer can say whether or not their investment was worth it to them and there are a lot of factors in that consideration -- well beyond the performance of the lens itself. AND that is their issue alone.
I sold my last OTUS lens recently (as part of my sale of all the remaining Nikon F-mount lenses in my collection) and I was sad to see it go. BUT - it was very big, very heavy and for shots that need a 24mm I have moved on to Medium Format (well small MF - X2D-100C). I have kept the tilt/shift lenses for now.