These features are mainly due to motion-picture/video lens design rather than sensor or tube protection.

A fully closing, clickless aperture is useful in video because it can be adjusted smoothly and silently during recording. Cinematographers can iris the lens in or out without audible clicks, and a lens that closes completely can be used to fade to black.

Still-photo lenses usually use clicked aperture stops because photographers want fast, repeatable settings. Smooth movement between stops matters much less when capturing a single frame.

The rectangular or square vignette/mask is a framing element used in some lens designs. In many still cameras, that function is already handled inside the camera by the film gate, shutter opening, or sensor-area framing, so a built-in mask in the lens is often unnecessary. Some lenses include such a frame, some do not, depending on the design.

So the short answer is: these are mostly practical cine/video features retained because they are useful for filming, not special calibration or wear-protection mechanisms.