Soccer is a very rigorous sport. In fact some of the top athletes are soccer players. With the amount of countries competing and rest time factored in, the World Cup sits at a perfect time frame. Factor in travel time and it could literally be extended. The fan base is also growing every four years so the hype continues even past the games themselves.
Wi th that many teams in the tournament I think it needs to be as long as it is. The teams have to rest between games because otherwise the competition will just turn ugly and won't be as competitive. I would say the world cup is more similar to the olympics than the super bowl. It's not going to happen in just one day, it's an event
Since the World Cup only happens every four years, it's very reasonable that the tournament take longer, similar to the Olympics. The length of the tournament also helps create some return on investment for the host country, which invariably needs the increased tourism revenue to offset the cost of venues and security.
Citizens across the globe get pumped up for the World Cup every four years; Why? Because it's fun. It's fun to associate and pretend to be a part of something so popular and globally uniting. It's the same concept with the Olympics, only it's only one sport as opposed to the many included in the Olympics. The more time spendable watching the World Cup is more time the world can spend bonding, and for this reason the World Cup is not too many weeks long.