I couldn’t agree more… and would want to take it a step farther. As a programmer, my IDE requires tons of modifier chords (Ctrl+Shift, Ctrl+Alt, Alt+Shift, and the dreaded Ctrl+Alt+Shift). This is the biggest cause of typing discomfort for me. Minimally, I need to do all those chords on one hand, without major contortions, while typing the modified key on the other hand.
I’ve envisioned a layout where, on say the left hand, you use a thumb key that changes the layer of the left hand such that the Ctrl, Alt, and Shift keys are mapped to the home keys of the index, middle, and ring fingers. Thus chording of the modifiers is easily done with the left hand as you type the modified key with the right. A corresponding thumb key on the right just reverse the process.
That may be more than most users desire. For the sack of this discussion, I would basically want it so I could tweak the layout that one of the four thumb keys can be used for my alt layers. My current plan is to buy a set of Dvorak keys, used for most keys, and then blanks I can use for the few keys I tweak. I find blank keys a thousand time easier than a key with false info (due to a remapping).