Something that occurred to me...
If midichlorians are just cells living inside a living host, and total number of midichlorians determines just how powerful you are in the force, wouldn't removing a substantial amount of blood in the form of robotic appendages significantly reduce the midichlorian count, thereby making you much less powerful?
Seems like Darth Vader should have lost quite a bit of his force powers when he got robotic legs and arms.