It's still Google. Rather than move into something else (say Edmodo), students are using a platform/program that is already being used. Perhaps this is a good thing. From my point of view, I like adding something a "little" new.
There are few easily available collaboration ideas like awards, quizzes, polls, avatars. Each of those can be added through googleapps but not as readily as something like Faceboook or Edmodo.