Remember that Jeff is also taking lessons on how to be a nice guy from Rich lol. This is probably a progression of that teaching! Pierce has always been an ass hole and now even more so since he's been on the pain medication. He's selfish and doesn't like being left out of the group. Britta has annoyed them since the first season with her self righteousness ultimately that's an side effect of her trying to be a good person. Annie naivety has been addressed on multiple occasions...Jeff's even yelled at her for it on a couple of occasions.
The thing about these characters are that their flaws are what brings them together. Troy and Abed have the one true genuine friendship that's true, they're the heart and soul of the group but the others realize that they're better when they're around each other.