In this case, there might be details about a character in this design that aren’t ever important, but in the era of massive franchise filmmaking, these sorts of things need to be dealt with at the beginning so that, if and when, issues like the techno-organic virus become important later on, the work was done at the beginning and nobody needs to retcon anything.
It’s always interesting to see the evolution of different ideas as they eventually culminate in what ends up on screen.
Things like costume design, or in this case, arm design, are meant to tell you a lot about a character without having to spend screen time explaining things.