A waist pack or a messanger bag will be a lot less obvious and might save the rear element of your lens. Bayoneting a lens to a device at one's waist at an odd angle is a bit acwared and risky. If there is a slip it's a plastic cap v. metal bayonet.
I think this is a great idea for selling and a poor idea for buying.
Dave the cynical
You seem to be missing the ethos of the usage.
Nevermind that you are professing on a visual and not on real life experience.
It is about "FAST" change of lens on the go.
Your experience is: Open the messenger bag - locate the lens - unscrew the cap - put the cap in the bag - unmount the lens on camera - place the unmounted lens in the bag - replace cap on - mount he other lens on the camera.
The Capture Lens goes like this: Unmount the lens on camera - mount on Capture lens - Unmount the lens on Capture Lens - Mount lens on camera.
Which is more practical and which is more efficient?
N.B. The Capture Lens mount is not plastic but metal