Armrests do seem to facilitate lighter and more consistent inputs using wrist movements. Finger tips are indeed good. On the other....err....hand (?) armrests also provided something to lever against when the need arises. They help a lot if your wrists become tired. Changing hands is, of course, a good way to share the workload.
Personally, mine's always up for take-off and landing (it's the excitement, I think), but it varies a lot for other situations.
eg - Up for hostie refreshment visits, to avoid making a mess. Up in turbulence (similar to top-deck bus rides, I guess).
I certainly don't think that Management should dictate in this respect, despite their proven record as experts in the skills involved.