>>Why stage? Git’s flexible: if a, b and c are changed, you can commit them separately or together

This is the saver I would say. More often than not it so happens that once I am done with an implementation/issue, I get carried away (I am working on fixing this habit) and continue writing code in order to get as much out of me as possible and then suddenly realize that one of the earlier fixes should already be in the repository. Thats when git staging comes into picture.