They refused to vote on a highly qualified nominee because they didn't like the party of the president that nominated him. It was and remains an unprecedented action taken by one of the most hypocritical men to ever work in the Senate, and that is truly saying something.
It was a stolen seat. Unfortunately, the American public pulled the equivalent of jury nullification and signed off on the theft.
And I doubt you'd be saying the same thing if the court wasn't already 5-4 in your favor.
He might have been highly qualified but he didn't believe in the second amendment. The court is 4-4-1 right now and that is a good place to leave it. It will be interesting to see who Kennedy's replacement is.