They left Brent Seabrook off the team because he Shoots Right Handed.
Yes, that and the fact that Seabrook looked slow in Vancouver 2010 and was demoted to 7th defenseman by the medal round. Subban also was in the press box because he was right-shooting and couldn't supplant one of Weber, Doughty, or Pietrangelo. Canada gave up three goals the entire tournament and a defensive group playing their strong, familiar sides of the ice was a significant contribution to that.
As for Carter, he was played a big, mobile game all tournament at both ends of the ice. Remember when he outraced Grabner to the puck and stopped a breakaway? He also used his size and speed numerous times to drive the play towards the US net in the semi-finals. Overall, somehow I cannot imagine Babcock letting a floater play on Canada's shutdown line (who received heavy minutes) and the PK. The only times I watched Carter "float" was during the PK when he was executing his role as the defensive player covering the middle of the ice as the other team brought the puck out of their zone and then he transitioned to cover the winger attacking the far side of the ice. His role on the PK at that point was to float through center ice.
Hall will be a better player then Kunitz, but this year Kunitz was stronger in all three areas.
Still imagining a top line of Hall - Crosby - Stamkos sounds god damn terrifying. And if Eberle regains his form and works on his d zone Canada would take him for his clutch goals in international play.