I think it boils down to UI navigation. With a window manager, terminal, and an editor/IDE I don't really need to use the mouse to work effectively as a program

I think it boils down to UI navigation. With a window manager, terminal, and an editor/IDE I don't really need to use the mouse to work effectively as a programmer. Once my muscle memory adapts to the keyboard layout, I'm set. However, navigating a 2D schematic/PCB/drawing or a 3D part with a touchpad is a nightmare and most software doesn't support the touch screen mechanics that I need to effectively replace navigation with a physical mouse. Even with a 3dconnexion portable 3D mouse, there's just too much clicking and precise movement involved in a UI like Altium or Solidworks to be usable. That and I've never seen a portable laptop that can handle a Solidworks multi-hundred part assembly or a 20 layer Altium PCB, except for massive 17" workstations that are ostensibly laptops.