There were too many times during a free kick when players would start creeping past ten yards and get way too close to the kicker in an attempt to mess him up. I think this is a great idea and everyone will be able to tell right away if players are breaking the rules.
Yes, the new vanishing spray for free kicks will make the World Cup more fair, because they had a big problem with defenders inching too close during free kicks. The vanishing spray is a brilliant way to solve the problem. It puts a line in the sand, so that defenders can actually be penalized for crowding.
I did not see a need for the change to occur. While players were able to gain an advantage for the kick, both teams were able to do it. So in actuality there was no advantage for either team, just shorter kicks. Now the referee must take the time to spray a line onto the field. It disrupts the flow of the game.
Of the handful of World Cup games I have seen this year I have been very unimpressed with the "fairness" of the game mostly due to the referees. They have way too much power over the game and one bad call in the box can drastically change the entire game. The refs are very inconsistent and even seemed like they favored Brazil in Brazil's game versus Croatia.