I read an article tonight that said that Thomas was not exactly known and some of his rulings were "Souteresque". What if everyone had listened to that?
The simple truth is, you don't know how someone is going to rule once they get up in that high, thin air. You can only count on their judicial philosophy, and Dubya is in the best position to know that.
By not waiting until you have a better understanding, you risk being the pressure behind eliminating someone who could possibly be of the calibre of Thomas and Scalia. Or, she could possibly end up being as squishy as another Kennedy. We just don't know until we listen to what she says in the hearings.
That is just a form of gambling? Why not just invest your money by picking stocks at random and hoping that they might be the next Google? It might work out, but it would just be a matter of luck.
It is always a more sound practice to pick a known quantity.