I think the whole Korra generation is more advanced than Aang.
Aang was able to remove and restore bending abilities, but during Korra's time, the first villain could do the same thing. Metal Bending, Lava Bending, Lightning Bending, and bending things inside other people are all fairly commonplace, too. Aang knew that these were possible, but there were only one or two people that could use each bending technique. By comparison, Korra can also Metal Bend, and presumably could also learn the other abilities.
I mean seriously, in the last season alone, people were using Air Bending to suffocate people, and another person had her head encased in metal while her face exploded. None of this would have happened during Aang's era.