Why still manual lenses?

The ultimate practical reason for dedicated manual focus lenses is videography: Autofocus is seldom if ever used by professional videographers and cinematographers. It's very difficult to use autofocus with video, and the hunting back and forth that autofocus requires is not an appealing look in video.

A manual focus lens with a long, buttery smooth helical is much easier to use than an autofocus lens with a manual focus ring that goes through the entire focus range in a quarter of a turn. You can get the focus just where you want it easily with the former, with the latter it's a lot more fiddly.

When pulling focus, cinematographers want absolute consistency in focus distances: they set up a shot for a few different focus distances, and they want those to be the same no matter what. But the vast majority of focus-by-wire lenses actually are variable in their sensitivity. If you rotate the focus ring slow, or rotate it fast the same distance, the focus doesn't end up in the same place both times.

It's a lot more difficult than you'd think to get both an AF system and a good manual focus feel. So the different lenses are ultimately for different purposes.

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