Why? Because that means an entire "thread" of U.S. Supreme Court case law would go down and you have no idea how broad and systemic and pervasive it would hit us all. And, this "thread" of case law has branched out over the years similarly as does a tree with all its many branches.
The entire "privacy" prong of the constitution which is an "inferred right" not an express right in the constitution. Yes, privacy! abortion rights, condom distribution rights, privacy right of families, the right to die with dignity, the right to be left alone, stem cell research, etc., etc., etc. The list is about 100 hundred years old. Good, strong settled law.
And it's this list of privacy rights that Justice Antonin Scalia has been salivating about -- wanting to chuck it away. This is why Judge Bork wasn't seated on the U.S. Supreme Court, b/c he wanted to turn settled case law on its head. And this is why Justice Thomas wants to over-turn all this line of law too. After all, he cannot distinquish between his Roman Catholic God and the constitution.
upon edit, added:

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"I believe that it points up the fact
that we need common sense judges who
understand that our rights were derived
from God. Those are the kind of judges
I intend to put on the bench." — GWBush,
June 27, 2002, explaining his litmus
test for federal judicial nominees.
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