The cost it would take to convert manufacturing from the way zoom lenses are made today, and the retooling and re-design of lens bodies, lenses, auto-focus, focus motors, etc., would make the concept cost prohibitive. Lens makers have spent years and lots of dollars to improve zoom lens designs from the old push-pull design to today's helical mounts, and no one likely would be interested in reinventing the wheel.
A lever-operated zoom is more or less a push-pull with a mechanical device added.
Besides, until someone can show the failure rate in today's designs to be excessive, no one will change.