They're going to make it worse. The way you build a good community is to make player reputation matter and make it impossible to achieve things alone. That way players have incentive to work together. LFD/LFR do the exact opposite: you can achieve everything alone, so you're free to be as big of a douche as you like.
Nobody is going to care about your "Summoner's Code" and Blizzard can't start mass banning "toxic" people because they are losing too many players as is.