They aren't mutually exclusive. And GAA still doesn't speak as directly to goaltender skill.
In every single NHL game (non shootout) the goalie (or team) with the lowest GAA wins the game guaranteed. The goalie with the best SV% doesn't guarantee anything as the goalie with the better SV% could be the losing goalie of the game.
So which would you prefer your goalie to have the lower GAA or the higher SV% in a game?
If its personal players stats you like then SV% is for you, however if your focused on team wins and losses then GAA is what you will be focused on. Games are determined by how many goals go in, not how many pucks a goalies stops unless he stops them all.
Skill evaluation is a completely different intangible evaluation and not restricted to SV%. Fleury might be on Team Canada in the Olympics ahead of Reimer or Bernier regardless if the Leafs goalies have the better save % at the time.