The Constitution was amended to change your first two examples. The last wasn't officially Unconstitutional (though violating our treaties repeatedly was illegal). Actually, genocide still isn't Unconstitutional per se -- or if you argue it is, it's not the murder part you're arguing is Unconstutional, but rather the implied violation of equal-protection.
Basically what the point is is that the Constitution isn't meant to address all evils, be a moral code, or even a penal code -- it's an organization of governmental powers, with some specific powers granted the federal government which have morphed into almost a general power, and some very specific limitations on the application of that power with respect to individual citizens.
No, to follow the document written in 1787 and as amended is NOT to say the world has not changes since then. It is to say that there was a point to having a written Constitution passed by a supermajority, rather than simply a floating conception of common law that changes with time (Hello British folks).
If the world changes, amend the Constitution. And if you can't amend it, maybe the world hasn't changed as much as you thought...
BTW, this isn't to say that you can't apply principles to new situations - it's not legislating from the bench to fill a gap in the idea of "search and seizure" as it applies to computer files. To the extent judges need to do that, they should apply the concept as it was intended when the law/Constitution was passed, and be true to that principle when applying to new facts. That doesn't mean changing the meaning of something so that it applies differently to something that has existed forever because a few people decide "society has changed," which is what would happen if some judge decided that the Constitution decreed gay marriage must be legalized.
As I said, if society has changed, amend the Constitution the proper way -- if you can't, then it hasn't changed as much as you thought. And whether that's right or wrong, the fact that you can't simply decide it means something new is as much a protection of individual liberties as anything else.