Why stagger columns like this?

One of the noticeable features in my design is the column stagger. The innermost index finger's columns (TGB/YHN) are higher (or rather farther) than the next ones (RFV/UJM). The same for the outermost pinkie columns. I frequently am asked why, the short answer - it makes the keyboard use much more comfortable and less painful. Many if not all other ergonomic designs place the columns in nice smooth arc, with the outermost pinkie column is at the same level as the pinkie home column. It may a gentle curve like Sofle in this picture, or it could be sharper in some other designs:

That looks ok for the static hand position, or with the slow finger movements. Like when someone started designing the layout based on one's hand. In my experience such design this design is causing significant discomfort and hand pain. The up and down movements along the columns are ok. Isolated lateral palm or finger movement, i.e. when the whole hand moves sideways but the fingers are kept at the same position, or the palm remain static but either the index finger or pinkie move sideways a bit, that is all ok. The problem appears when the index finger or pinkie curls in combined with later palm movement - that is felt as a strain in the palm. Green lines show "easy" comfortable movement ranges , red ones - where it starts hurting me.

To me it seems like there is something in the hand structure (bones, sinews, whatever) that does not expect such movements. I also noticed something else - when the palm turns right or left, fingers are extending in that direction. You may try that yourself. Put your right hand on some wrist support, and try to turn the palm to the right, keeping the fingers relaxed, curved as if they are on the home row. Most likely your pinkie and ring finger will extend, stretching out a bit to the right and away from you. Similarly, when you turn that hand to the left, the index finger and, to much lesser extent, the middle finger fill extend. That seems to be normal action for the human hand. Now repeat those movements, but this time try to resist such involuntary finger extension. For me that feels like a pressure in the palm, like some contradicting forces are pulling the base of index finger when palm moves left, or the edge of the palm and the wrist when palm moves right. I understand it as when the palm is turning the fingers better be extended than curling in. Ok, that may be me sensitive to such movements, but since we're all built the same way I suspect the same tension appears in almost everyone's hands. Hence I moved the outermost columns higher, getting W pattern instead of an arc.

Interesting enough, in this picture for the pinkie the movements are the same as for Sofle, mostly because in the latter the pinkie columns are at the same level, and I raised it by 2 mm only. For the index finger the angle is different, and the movement from J to N requires the hand turn only. The finger itself remains relaxed, so there is to contradicting force in the palm. It is not obvious from this picture, but the difference in the key level keeps the hand from complete pronation, so the index finger actually extends a bit with J-to-N move. As for other two moves, J->H, J->Y, the movement is even easier, no need to control the finger much. Its natural tendency to extend just needs some tiny help, so the muscles moving the palm and finger are moving in the same direction, assisting the natural move. Hope that explains the reason of such W-shape staggering.