FWIW, Kagan was a lot more worthy than Sotomayor. Kagan is a smart, capable lawyer well-liked by leading lawyers and leading academics from all ideological corners. Sotomayor is a thorough mediocrity who did one thing well in her career: managing to be in the right place at the right time to be “first Latina to do X” — there are a dozen liberal Latina law professors whom Obama could have drawn from but he was too risk averse to do anything but appoint a Circuit Judge.
I would argue the opposite, although I think both are ultimately the same side of the coin. Sotomeyor had a long and distinguished judicial track record. Yes, her race played a part, but probably no more than gender in both of these cases. If I had been a Senator I would have voted for Sotomeyer as it is the President’s role to nominate someone as long as their is not corruption or lack of qualification. In Kagan’s case, she was already decided on any number of issues in front of the court coming from her position in the administration. She’s corrupted going in (not corrupt, but biased).