That is very important. Many people flat out refuse to understand this. They want to believe that these rights can be given up, taken way or transferred to another by a majority vote, or because some law making body says so. And some want to use the "States Rights" argument to support their claim. Unfortunately, this principle applies to all levels of government.
Yes. Unfortunately this was the instrument to enslave blacks and later protect "Jim Crow" laws. Too bad. "States Rights" could have been an excellent tool to keep the Federal Gov't. in check.