This question is a little vague and I hope I can put across what I am looking for without too much confusion.
What is the motivation behind studying asymptotic symmetry groups in the context of general relativity? How is it important in the AdS/CFT correspondence? I have also read that the study of the ASG plays a role in understanding scattering as well. Why?
NOTE: I know what the ASG is. At least I think I do. I do not want to know how one goes about deriving it, etc. I am asking a more general question about the motivation behind its study. Indeed I am more interested in the motivations to study outside of the AdS/CFT correspondences and the likes. However, if you think the derivation of the ASG gives one some insight into this question, then please also mention that as well.
PS - I am not just interested in the ASG of AdS space. I simply mentioned an example here.