Well, these kind of augmentations are, in a way, forced. Because nobody wants a cardio helper, or prosthetics if they don't need them. 
But I think, there will be a time when technology will give us the option to choose to add an augmentation. Better sight, higher strength, etc. 
Although, it will be created with military purposes, but, almost every piece of technology was created this way. 
I agree with you, we are not prepared for that kind of discussion yet. What makes a human, human?