It is linked with tradition, these were always around in the film era, there are at least ten different one - including Canon FL -What's the deal with these weird focal lengths, 58mm and such?
But of course there was a Noct-Nikkor 58/1.2 and this is sort of a modern successor.
And they also have a 58/1.4G in F-mount as well, which was like "an initial greeting of the old legend, before the true successor arrives".
It is the longest focal length with the f0.95 aperture so far.
So in a way it is a statement, a new standard. Just like what Canon did with the F 28-70/2 (coincidentally)
Even more special (and expensive) and also manual focus, so not nearly as useful.
But there is a manual focus Leica 50/0.95 and people are still buying them, so...
But, 58mm is yesterday's news anyway, a 65mm f/2 APO-Lanthar Macro is even better in terms of weirdness
All relative anyway, just because 50mm is the standard, it can be considered 'weird' in some people's eyes.