How many times did you see forks lying around on github?
How often did you notice the annoying message "This branch is X commits behind awesome-project:master."?
Why did you fork it in the first place?
Was it an animal instinct of yours to click on a shiny button?
A great man once said:
commit your changes and rebase on upstream/master; the project needs it ~ gandhi
What I am trying to get across is that forking a repository just to have it lying around is a waste of everyone's time and attention.
Like branches should be short-lived, forks should be made with a commitment and small improvements pushed upstream.