The playstyle should depend on the player, not the league: if a player wants to use canon, pick r or one race, abusing spots, etc.
If the league is going to dictate even how you should play, then they're tying the players' hands. Remember that each player's style is their own, and when you play, the one with the most efficient style wins.
When Koreans play, they don't complain about canon; they just play, and their skill with their more aggressive style is what gives them the victory. It's not a good rule/format.