I think that's a red herring. Whether the keys are staggered or not doesn't have any effect on wrist position when you think about it. You rest your fingers on the home row. That defines your hand positioning, and your fingers handle the necessary corrections.
Well, I'm not going to say you can't start with your wrists in the right position.
However, I would think your fingers have an easier time "rolling up" or moving left-right than to do both at the same time.
When you keep your wrists in a natural position on this keyboard, your fingers are at an angle relative to the keyboard itself. So when they have to move on a matrix keyboard, they will have to move diagonally.
Somehow, I can't shake the feeling that this keyboard makes you take a bad posture if you aren't paying attention.
Of course, when you do relearn to type, you can learn to compensate for all ofthis. Still, I think that a keyboard which adapts to your habit is a better alternative, so IMO a non-staggered key layout might make more sense on a split keyboard.
Staggered keys are good for the right hand and very bad for the left hand - at least if you accept conventional wisdom on which fingers to use where. Overall I'm convinced staggered keys are 'a bad thing'.
The QWER row is only set 1/4 key width to the left of the ASDF row. I wish manufacturers would at least have the courage to line those 2 rows up as part of a gradual process of weaning the population off of staggered layouts.
Edit> Also the number row is 1/4 key to the right of the home row - still an easy change to adjust to even though the movement is bigger relative to the QWERTY row (1/2 key width.)
This is the "legacy" layout you are talking about, and very so, it is indeed a bad layout for your left hand and an annoying one for your right due to non-uniform shifting.
Still, I wouldn't say staggering is bad. If you'd change your keyboard so the staggering is symmetrical and uniform (e.g. 1/3 key), you could have a nice keyboard layout which works out OK for both hands. It would seriously mess up your muscle memory though as can be seen in webwit's comments on the μTRON (an interesting keyboard nonetheless).
Gradually shifting the rows by 1/4 a key every 5 years would be interesting. I think I read about that before, but I can't remember where.
I guess I'll have to build one or buy a matrix keyboard to make a final conclusion on this. Still, my common sense would tell me it is about as unnatural as the legacy layout, were it not that some matrix models do try to keep your hands away from each other by inserting more keys in the middle.
