When I started working for the Yamaha dealer in 1972 at 15 years old, the guy said that the clutch was for starting and stopping. He rode me on the back of a 250 Enduro to show me. Been doing it that way since.
My first shaft drive bike was an XS1100E and I usually used the clutch from 1st to 2nd and back to first. That was the first and only bike that I had to replace a shift fork and 2 gears. (Yes, I did that myself). And after 2 more Japanese and 3 BMWs with shaft drive and a bunch of chain drive trail bikes, I now have a 750GS with Shift assist ! I really like it, but it would not be a significant upgrade on a chain drive bike that came without it.