after not doing that in any other update I can remember
This is the first time I remember a Google Doc form. However a special email address or subject line has been offered for major updates for many years. In fact, years ago GoogleGuy would often offer that kind of avenue specifically for WebmasterWorld members. Even Panda offered a dedicated thread on Google's own forums.
I think this form input is simply a step toward giving the webmaster input more structure so that the information they are gathering can scale more easily.