There are ALWAYS going to be polarizing issues and periodic political turmoil of some variant and degree. A leading point of merit selection (appointment) is stability and an independent leg of the three legs of federal government from the whimsy of term service on the electoral system. Consider the stability of government where all three branches are subject to strong lobbyist (big big money) influence on decision making. A branch of government which serves as an appointed anchor provides stability, like the string on a kite. Cut the string and where does the kite fly?

While that is certainly the strategy used to place people on the court, it usually backfires on the party in power. Republicans appointed Kennedy, Sandra Day O'Connor, David Souter, and (for god's sake) Stevens. Additionally, even when dominated by Republican appointees, the court has whacked Republican administrations (most recent example: detainee trials).