The issue is not whether the world is ever-changing, but whether judges should treat the Constitution as ever-changing to meet their own agendas and desires, often over the lawfully expressed preferences of voters, legislators and the founders.
Still, if the Constitution is unclear or inadequate, what's a strict constructionist to do? Propose changes, and you're dubbed a hypocrite and a radical for wanting to "tinker with the genius of our constitutional design," or else you're guilty of hypocritical conservative judicial activism.
The relevant fact is that central to the genius of the Constitution's design are the mechanisms to change it. That process is arduous, requiring long and deliberate debates at the national and state levels. (In over two centuries, thousands of amendments have been proposed, 33 have been approved by Congress, and only 27 have been ratified by the states. That's not tinkering, that's craftsmanship.)
When discussing the Constitution on college campuses, students and even professors will object that without a "living constitution," blacks would still be slaves and women wouldn't be allowed to vote. Nonsense. Those indispensable changes to the Constitution came not from judges reading new rights into the document but from Americans lawfully amending it.
From birthright citizenship and gay marriage to flag-burning and gun rights, I trust the American people to change the Constitution when necessary (after lengthy debate) more than I trust five out of nine unelected justices with lifetime tenure, hiding behind closed doors and away from TV cameras.
What are the opponents of "tinkering" afraid of? I suspect sullying the genius of the founders takes a distant backseat to their real fear: losing a fair fight.