People won't do this for GoT in particular as the opening changes episode to episode and gives you a preview into the locations that that episode will deal with. A lot of people enjoy the openings and pay attention to them.
I liken it to the Simpsons or Futurama in the sense that things subtly change (e.g. locations which are destroyed in the show, are destroyed in the opening, and such).
Indeed. Not only this, but the opening credits also gives the names of the actors (which change from one episode to the next), director, writer etc. of the episode, which are unique to each episode.
I liken it to the Simpsons or Futurama in the sense that things subtly change (e.g. locations which are destroyed in the show, are destroyed in the opening, and such).