In 2014, the spin-o-rama shootout (and penalty shot) tactic was changed from 'explicitly allowed' in pre-2014/15 rules:
The spin-o-rama type move where the player completes a 360° turn as he approaches the goal, shall be permitted as this involves continuous motion. However, should the puck come to a complete stop at any time during the shot attempt, the shot shall be stopped and no goal will be the result.
(Rule 24.2) (Source: the above article)
The rule now reads, in part:
The spin-o-rama type move where the player completes a 360° turn as he approaches the goal, shall not be permitted. Should a player perform such a move during the penalty shot, the shot shall be stopped by the Referee and no goal will be the result.
(Source: NHL Rulebook)
What caused the NHL to choose to change this rule? And if the reason is considered solely the IIHF's decision to do the same earlier in the year or some other rule-making body's similar acts, what was the ultimate cause for that change? Note that the NHL does still explicitly permit lacrosse-style moves (where the puck is picked up on the stick and then whipped into the goal), while the IIHF banned those as well.
I'm specifically looking for evidence (cited evidence from a reliable NHL source, or at minimum a sportswriter with intimate knowledge of the game) as opposed to theories.