You can always right-click on a bag, select "Bag Options," and mark an entire bag's contents as "not for sale."
That way, all you're doing is dragging icons to and from certain bags. I use it all the time and designate certain bags as "stuff to sell to NPCs" versus "stuff to sell to other players," sorting items as I loot them.
(I deal with joint pain myself, and adopting this method has made my fingers and wrist much happer than they would be otherwise.)