I really do not understand how a criticism of an arcade cabinet accessory not being portable makes any sense.
Who expects what is essentially a bartop arcade to be portable? And to that end, the iCade IS relatively portable. It's mostly MDF so it's light and it's only about as big as a Vectrex.
I can't imagine anybody looking at an iCade and saying "Hey, this will clearly make for a great portable gaming experience! I'll use it on my lap, in the car, on the bus, in bed!", but whatever.
I have not encountered any of the space or strain issues that you have, but that's probably because I don't play with arcade stick setups with my wrists in a resting or supported position.