The purpose of the Courts is to dispense Justice. This will invariably involve making new law. If you insist upon saying this is just "interpretation" when you do it, but is some sort of over-reach when other people do it, I feel the same way as when I see a sports star insist they were "within the spirit of the game" despite cheating while their opponents aren't... (e.g. ball tampering in cricket is very bad for this)
The thing that's special about the courts compared to say, a legislature or executive government is that they deal only in Specifics. They must consider _actual_ things that happened and judge those. All those named cases like Brown v Board of Education are about real people, to whom real things happened. That's what the judges are for. It will be necessary, from time to time, in the process of achieving Justice for the people those real things happened to for the court to make up from whole cloth entirely new law, and a good judge should not shy away from this practice where it is necessary.
Sure enough "Originalist" judges do not, in fact, shy away from making up new rules to achieve justice. They use their "originalism" instead to defend situations which presumably _they_ think are just but which seem wholly unjust to their fellow judges, and they deserve nothing but scorn for that. Say what you mean, and mean what you say.