You are right Gordon. The volume hand controls only volume, and the pitch hand controls only pitch. What I am trying to point to is the number and the complexity of tasks within those two parameters that must be executed simultaneously.
The reason why control of the rod has been delegated to the right hand in right-handed people (and the left hand in "lefties") is because playing the rod requires greater dexterity due to the amount of, and relative difficulty of, the multi-tasking involved. As you pointed out, the volume hand must execute a number of techniques related to volume (staccato, tremolo, crescendo) but it generally does not have to do them all at once. In fact, on a theremin, you cannot play a staccato and crescendo at the same time (something that is relatively easy on a keyboard, violin or cello) because the resources needed for the one, are the same as those needed for the other.
The other thing about volume control is that it does not demand the same degree of precision as pitch control. All things considered, it is an easier skill to master.
The pitch hand has to do a number of things at once, and it must do them with a degree of accuracy that is rarely required of the the volume hand. Intonation, vibrato, portamento, etc. must be done exactly and simultaneously (and preferably not with the same muscle groups).
"omhoge" wrote in his original post, "I'm working on pitch and getting it into muscle memory, so I can focus 80 to 90 percent of my attention on the volume hand...", and it is really this decision that I am addressing. We all hear music differently and om's shift in focus may indeed take him to the place he wants to go musically. Whether or not it will be as satisfying to others as it is for "om" remains to be seen......or heard...
Thereminist Kip Rosser has developed volume control (in particular, articulation) to an astonishing degree, and he is to be congratulated. I am not certain, however, if general appreciation of his accomplishment equals the tremendous amount of effort Kip has put into acquiring it. There has been a trade-off and in the process, for some listeners, the baby may have been tossed out with the bath water.
We have only ourselves to please. If a thereminist is satisfied with his or her work and enjoys playing the instrument, then it's MISSION ACCOMPLISHED. As I have said many times, no matter what you do, or how well you do it, some people will like it and others will not. The other day, you and I were discussing a particular performance of a composition by Percy Grainger and you mentioned that it actually made you feel nauseated. Reading over the comments from other listeners I noticed, with some amusement, that a number of people said they could not listen to the piece without tears coming to their eyes.
Some people cry, some people throw up.