Notice the gear teeth at the base of the lens? Cine lenses are designed to be used with a Follow Focus mechanism.http://en.wikipedia.org/wiki/Follow_focus
I'm not a cinematographer, but my understanding is you want all your lenses to have the exact same diameter so you can switch lenses and not have to adjust the Follow Focus gears.
So the 24mm prime has to be the same OD as the fattest zoom lens.
You also want the distance scale visible from the side and the behind since there are usually two people operating the camera - one to frame the shot, and the 'focus puller' to adjust the focus, and the puller needs to see the distance scale since they don't have a viewfinder.http://en.wikipedia.org/wiki/Focus_puller
The other natural question is "why are Cine lenses so much more expensive than still lenses?" and the answer is that they have to be designed so they don't 'breathe'. In a still prime, when you focus, there is a tiny amount of zoom happening - but since you're taking a still photo, it doesn't matter. In video, if, when you focus your image size changes - it becomes very visible and annoying. They call it breathing. http://en.wikipedia.org/wiki/Breathing_(lens)
A Cine lens is designed to correct for this, so the image is perfectly the same - throughout the entire focus range. This correction is difficult and expensive... and adds no value if you're a still photographer.