Never understood the need for 3rd place match. Other than some monetary intensives -- on emotional level who really cares? Even 2nd feels a terrible world cup loss when you get this far and lose.
That comes from the origins of the World Cup. It all started in 1924 during the Paris Olympic games. Uruguay won the football tournaments and called themselves "World Champions". However, the tournament was supposedly "amateur", not all countries brought their best players, yet some countries disguised their professional players as "amateurs", in inventing them fictitious professions.
That's how Jules Rimet, the President of FIFA who organized the football tournament at the Olympics, got convinced we couldn't do without a global tournament open to professional players. The Olympics won't just do it. He'll spend all his energy during the 6 next years to make it become a reality.
As such, the world cup was initially directly inspired by the Olympics, which distribute gold, silver and bronze medals. That's the reason why there's been a 3rd-place playoff for the first world cup in 1930. Then world cup has grown over time, and the 3rd-place playoff became a tradition. Some minor nations which were already glad to have reached the semis, like Croatia in 1998 or Turkey in 2002, actually played the game very seriously, because they really considered bronze as an achievement. This has been the case as well for France in 1958, and probably others. However, it's obvious that the most desappointed losers are devastated and don't want to play it. Very often, it is played by substitutes who are just glad to play a world cup game.
Personally, I'm a bit of a traditionalist so I don't really mind it. Furthermore, I have the feeling it gives more importance to qualifying for the semis. You know after the quarter-finals that, no matter what, you'll stay untill the end.