Because "there has to be" at least one woman on the SCOTUS, just like in the past there "had to be" at least one Jew (the 3rd seat occupied first by Cardozo, then by Frankfurter, Goldberg, Fortas, Blackmun, who was the only non-Jew in this seat, and now by Breyer is even sometimes called "the Jewish seat") and at least one Catholic. Now we have a "black" seat (do you really think GHWB would nominate Clarence Thomas if it wasn't Thurgood Marshall who retired?) and it's rather obvious that there is one place reserved for a woman. Affirmitive action has applied to the SCOTUS appointments for a very long time, I'm afraid.
I'm familiar with all the "seats" - the "Jewish seat," "Black seat" and "Woman seat." It is interesting that the MSM said that Bush HAD to nominate a woman to replace O'Connor, but didn't.
Alito's nomination showed that if the person is qualified (and Alito certainly was), it is hard to argue that the seat belongs to a certain group. Remember, the "Jewish seat" disappeared for a few years until Clinton nominated Ginsburg. Now, with Breyer, there are 2 "Jewish seats," to go along with 5 "Catholic seats." (Oh, the horror!)
Alito's nomination proved that the Libs are paper tigers. They can yell and scream all they want, but they cannot block a highly qualified nominee - even if the nominee has a long track record as a Conservative.
I hope Bush crams through another Strict Constructionist, whether it be Luttig, of JRB.