There is a difference between resigning and retiring!

Punk RESIGNED( quit by self ) due to lack of interest and it is more complicated one. He now gives a damn about WWE like Goldberg.
To add further - WWE had very big plans to feature Punk as main superstar representing the company but all got shattered as Punk was not willing to continue anymore and WWE had no options except to carry out only one of the completed assignments out of few agreed( means, around 3 of their major plans were dropped due to this unexpected exit ). Their plans include many like games, animated cartoons etc.