The Champions League is an excellent example of how to combine a double round robin format with matches. Ok, chess will require matches that are longer than two games, and instead of "home and away", it's white and black.
The main failing of a series of matches is finding the funding for, say, Gelfand-Grischuk as opposed to Aronian-Carlsen. But if FIDE used the 8 player double round robin to select the top two players for a match, they could have the best of both worlds; a great double round robin tournament to draw in the fans, and a tense match to please the purists.
What we get instead of a Candidate finals match between Kramnik and Carlsen (or Aronian and Carlsen if those two had finished first and second), is the person who beat up on the 6th place finisher most efficiently qualifies to play for the next world championship.
My thoughts exactly! The winner of the tournament with this kind of format is the player who wins more against weaker players.
And by the way, to go slightly off topic... This is one of the reasons why Barcelona does better in La Liga than in the Champions League (in addition to the fact that the teams in CL are generally much better).