You don't have to switch between for multiple games for it to be useful.While i'm sure the feature will be well used by people who like to hop between many games (i'm not one of them), I really don't think I would label Quick Resume as one of the most next-gen features but maybe I would have a different opinion if I too skipped between 5 different games like a madman.
By being a system wide feature means you always get the benefits even in old games. Which means it's going to be more useful than features that requires dev intervention like activities.