The most popular sport in the world is soccer, of which, the vast majority of players playing soccer, currently are not required to wear headgear. Yet, in a sport in which heading the ball is part of the game in order to score a goal, or to control the ball, and in which head-to-head contact occasionally occurs when two players go after the same ball, or elbow-to-head contact occurs when one player leaps with his elbows raised; we find that all of this contributes far too often in player's receiving concussions, and concussions are not good for human beings.
The reason that a person's head is so important is that the head carries the brain, and damage to the brain, can have not only short-term effects that are negative, but can also have detrimental long-time effects, as well. This thus signifies that to the degree that concussions in any sport can be reduced or negated, then it probably behooves that sport to take a serious look at this, in order to protect the health of the participants in that sport.
In fairness to the sport of soccer, past participants in that sport, that have been known to have suffered concussions on more than one occasion, should be cognitively studied so as to ascertain how damaging repeated blows to the head, causing concussions to that player, are to the long term health of those players, and the results of those studies, should be peer reviewed and published. Additionally, to be proactive in requiring headgear should never have to wait until the studies of such are definitive, and without question; but rather should be done when the preponderance of evidence so produced, shows cognitive damage from head-to-head collusions and the like.
In recognition, that sport in the scheme of things, is basically a form of exercise, entertainment, and the application of skill-sets in a team environment; this should not necessitate players unduly being in danger of suffering from cognitive decline through concussions that could have been mitigated through the proper usage of headgear. Because of the nature of the sport, head-to-head collusions are going to happened, as well as elbow-to-head; in addition to the fact that players also head the soccer ball in order to score a goal or to pass the ball to another player, so that, headgear is obviously a prudent requirement to have for players, for their own good health.
Obviously, it almost goes without saying, that any sport that involves contact so dramatic so as to cause a player a concussion, and in which that sport per the rules of the game, has no intention of dramatically changing its rules to preclude such; therefore needs to take into account that the player's mental health, should not have to be impaired to such an extent by playing a particular sport that it damages their mind through that brain injury, so that the consequence is that it negatively impacts their concentration, their memory, and their enjoyment of life. This is why it is important to first study and to understand the potential damages of a given sport, and then to try to ameliorate such, with equipment and rule changes, as necessary, that addresses those very points.