Prince of Dzun,
I agree 100%. .I use to fly with 250h TT F/O on the fuel converter, and I've done the same remark to these guys : "Try to use the armrests, your flying will be more accurate, more smooth". The answer is allways the same : "No, no, I don't like that".
It reminds me, when I was on initial training in the Air Force. The instructors were telling us something like that, 20 years ago..."If you don't use the armrests, you'll never be a good pilot". That's probably why the C130 F/O are using the armrests.
Concerning the responses you've got up there, it denotes some little experience of flying heavy airplanes.
Cheers,
And here is the second main remark :