Look at the Colts/Bears SB. You had not only the Bears awsome returner Hester, but the colts terrible coverage. Do you understand what kind of an advantage you have when Hester runs 1 kick back, and all of your other possessions start at the 40? You are almost already in FG range with a strong legged kicker.
How about Jeff Feagles directional kicks? I used to think you always wanted the punter with the strongest boot, but having a guy that can pin opponents inside their 10 and 5 yardline is so valued.
The only complaint I have about John Carney is that he has a weak kickoff leg. The other teams returners catch the ball at the 5 and 10. I strongly advise teams with older, accurate kickers to keep a kickoff specialist. It is NOT a waste. If you have a guy that can give you an extra 10 yards on every kickoff, and you kick off on average of 5 times per game, that guy is giving you an extra 50 "hidden yards" that you don't have to defend. Would you rather have some backup LB, lineman or WR who never plays or only plays special teams, or have a guy that gives you guaranteed better opportunites at the start of drives.
It isn't for everybody, but the teams with the weak kick off guys should all have a kick off specialist.