Yeah just saw the comment. I'm not sure how difficult that system would be to implement or even fairly judge, since what's considered "big" or not might be subjective. Some people can crank out a lot of content in little time, while other people might spend weeks accomplishing the same thing. I'm sure most people would handle it fairly though and there's be a good middleground for it.
All that said, I'm in favor of encouraging people to make bigger updates and improvements. The point of comments and criticism is to offer advice so a person can improve their storygame, so taking it down and greatly improving it is definitely in the spirit of the site. Furthermore this system would let people feel more inspired to go back and improve older projects, that they might have otherwise called "good enough" and left as-is. And for readers, it may even get people to replay a storygame they already tried and rated, to see if it's better, and bump up their original rating if they improved on the areas suggested.