At the very least I feel like the A or the B button should have been where your thumb should naturally rock back towards. Instead there's no button in that direction.
(I guess there's maybe a rockable X button, kinda)

I missed the GameCube generation, but just recently have gotten into it. I've got to say that, honestly, the controller is awful for multi button combos.
The controller is design do solely for A + B combos, and if I'm totally honest, even those don't feel all that comfortable.