I have many ideas how I would like too have something like this in game: take too much damage buy a new arm, too much Nurgles-rot so you need a sealed liquid-based breathing system, not feeling close enough to the Omnissiah so remove empathy part of the brain and get some cogitator.
This could be used as just a fluff/esthetic thing. Or, as I would much more like, somehow replace the level requirements on some items, or indeed make them a requirement in themself to be able to interface with other implants and/or weapons. Ofcourse such a change to the human body should come with some sort of downside.
I can further flesh out concepts if people find this something they would like to see in-game.
Join in and explain why it is/it isn't something you'd like. Add your own take own the notion, or simply leave a wall of text explaining the in-effective time consumption implementing and balance such a thing would be.
Vlricus von Kronstadt