Genuinely not trying to be argumentative - But I think the "Who cares, he wouldn't be doing it in LA" arguments were/are more centered around the fact that Faber wouldn't have had the opportunity to do what he did this year in Minnesota if he had signed/stayed in LA.
As others have pointed out, the Kings right defense is significantly stronger than the Wild's and that was the case going into opening day this year as well.
Doughty, Roy, and Spence (Plus Clarke) on the depth chart for LA to start the season - While for Minnesota we're looking at Spurgeon, Bogosian, and Goligoski.... There was clearly a spot for Faber on the Wild's right side - With LA, it's more debatable.
Additionally, and more importantly, Spurgeon was injured for the 1st month of the season - That created an even bigger hole on the right side for the Wild and an opportunity for Faber to step up and fill an unexpected need. He clearly took advantage of the opportunity and good on him for doing so but let's not act like that was a stroke of brilliance by the Wild coaching/management identifying that they had a star in the 21 year old d-man and choosing to give him big minutes over proven NHL defensemen as a result.
And I'm really not trying to take anything away from Faber, he's a sick player, took advantage of his opportunity, and clearly played well enough to earn the elevated minutes and serious Calder consideration.... I'm just saying opportunity plays a big factor in these things. We see it allllllllll the time in the NHL - players switching teams, getting an opportunity to slide into a bigger role with their new team, and they end up flourishing in that new environment/elevated role.
We can still fault Kings management for trading away a player they should've realized had star potential... But the argument that Faber wouldn't have done what he did this year if he had stayed in LA is pretty valid IMO and that's not a dig at Faber and not a defense of Kings management it's just a flat out reality given the depth LA has on their right side.