The current rules in place, regarding shooting strings in men's lacrosse, needlessly complicate the game and do not align with stringing rules of professional field lacrosse. Between 2010 and 2014, youth, high school, and college lacrosse head specifications and stringing rules were changed, with the explanation that the ball needed to be easier-dislodged from attacking players' sticks with less checks from defenders. Some of these rule changes were beneficial in that they did address and correct a legitimate concern regarding excessive 'hold' in the pocket, but these rules that ban the "U" shooting strings and limit the positioning of shooting strings are unnecessary.

This rule is redundant. Men's Lacrosse already has rules which specify maximum pocket depth, lacrosse head dimensions, legal stick measurements, and even how tape is to be applied to the shaft. Each of these types of rules aims to prohibits any field player from gaining an advantage when carrying the ball in their stick, by giving their pocket extra 'hold'. The lacrosse ball is roughly 2.5 inches in diameter, and the width of the narrowest point of the face of any field lacrosse head, by rule, is 3 inches. The rules disallowing the "U" shooting strings are redundant; since 2010, heads have had to be wider than ever before, so the amount of 'hold' which the "U" shooting string provides is lessened by lacrosse heads being wider.
This rule does not prevent a player from gaining an advantage. Players and expert stringers have resorted, and will continue to resort to unorthodox sidewall and topstring stringing methods in order to achieve a sharp, narrow channel in the pocket, to emulate the added 'hold' provided by the "U" shooting string. As these advanced stringing methods are not widely known or practiced, the "U" shooting string can add some 'hold' to simple sidewall patterns strung by novice stringers.
This rule does not apply to players of exceptional ability. For example, Lyle Thompson and Matt Rambo, both of whom played NCAA lacrosse after the "U" shooting string was disallowed, are popular for dodging through defenses while maintaining possession of the ball, enduring harsh checks from the opposing defenders on their way to the goal. Despite the rule outlawing adding hold to the pocket with a "U" shooting string, many players are skilled enough to hang onto the ball while performing such acrobat-like maneuvers, making the rule ineffective.
Goalies can still use "U" shooting strings. Although they do not handle the ball nearly as often as field players (midfielders, defenders, attackmen, LSM's), goalies, for some reason, are allowed experiment with different combinations of straight and "U"-shaped shooting strings to achieve the style of pocket they are looking for. many goalies use "U" shooting strings to add 'hold' and some 'whip' to their pocket; all field players should be allowed to do the same.
The NCAA's new shot clock. The "U" string may increase a pocket's 'hold' to some degree, but now, the amount of time that any player on any team can hold the ball is limited by the shot clock. The shot clock is good for lacrosse because it encourages players to move throughout the field and move the ball quickly. The addition of "U" shooting strings has no effect on how frequently players attempt to pass or shoot the lacrosse ball.
Continuity. It does not make sense for field lacrosse to abide by different stringing rules in youth, high school, and college than those  of the professional level. In both professional field lacrosse leagues, MLL and PLL, players can use "U" shooting strings and are accountable for the depth of their pockets and dimensions of their lacrosse heads and sticks. The game moves fastest at the professional level, with a shot clock and players allowed to utilize "U" shooting strings. It is reasonable to alter field dimensions and lacrosse stick length requirements according to the size and age of younger players, but it's not logical to prohibit nearly all young players from using "U"-shaped shooting strings, then allow professional players to use them.
I contend that the majority of players, across all ages, would not use "U" shooting strings in their pockets anyway, and they should not be forced to use them. Individual players of all age levels should be able to experiment with "U" shooting strings, if they do want to use them. Allowing young players to decide whether to use "U" shooting strings or not encourages them to learn about their own lacrosse pocket and consider other pocket types, which is good for the game!

The notion that a player utilizing "U" shooting strings is at risk of being hit harder or more frequently by defenders solely because his pocket has more 'hold' is simply untrue. Hard checks and defensive pressure are still, and will always be, a part of the game, regardless of the limits placed on such minor things as shooting strings. It cannot be ignored that the most-skilled players, professionals, play at the highest speeds and are able to utilize the additional hold provided by the "U" shooting string. I believe that every player, regardless of age should be allowed to utilize this benefit.

If we remove these rules, we offer more stringing options only to those who want more options.