The thing with current bionics is that they are not... mindful in the way they are in GitS. Today's bionic limbs are pale imitations of our natural ones, though they are leaps and bounds over the stationary or slightly mechanical limbs of just a few years ago. There is little reason for someone to desire an artificial limb if they have a healthy functional limb.
In GitS they were, for most intents and purposes, better than the real thing. You could have a cybernetic eye with built in night vision and multispectral imaging. You could have a better/faster brain. You could have ultra-precision hands, fantastic for certain tasks.
But it puts into perspective, at what cost do these improvements come. If at a certain point, you replace your body wholesale for improvements, can you be sure you are who you think you are? If you cybernetic eyes lie to you, how do you know? If you have brain improvements, can they influence your thoughts or implant biases? There is also the whole "Ship of Theseus" thing going on. If you upgrade/replace your brain and body slowly, are you still you?
There definitely is a lot of soul/conscience stuff thrown around as well, but the above is what stuck with me all these years.