[Klaus]

Not sure what the connection is with focus by wire..

Right, it's not there. I think the Canon / Sigma / Tamron DSLR lenses are the best in this regard, as they have neither FBW nor the clutch. Unless, of course, the user is super wary of inadvertently changing focus in AF mode by rotating the focus ring.

I've merely cited the dpreview video guy who loved the focus clutch on the Pana S lenses. I reckon it is because the focus throw is very defined - it isn't with focus by wire.