What is it like typing on a keyboard that's just a grid? Every keyboard I've used has had each row be shifted slightly which seems to make touch typing easier.
As an experiment, place your fingers on the home row and naturally curl them out/up or in/down and see how straight or curved the path they follow is. For me, on a normal keyboard, I find that the buttons above the home row are positioned well for my fingers but for the ones below, my fingers naturally curl over the gap between the keys, meaning I have to also bend sideways. With a grid I can press both the keys above and the ones below without any sideways motion (for the four keys on each hand above and below the home row testing keys).
Nowadays I use a kinesis advantage, though, which has not only grid layout but also has them in a curved height to more naturally let your fingers reach the rows without any additional movements and I love it. But even on a flat keyboard, I find a grid works better for me.