Interesting topic.
I think it's due to marketing/distribution issues. Perhaps Hasbro can reconsider its real market and address it accordingly. The ROC line is a good example of trying to retain old fans and bring in the kids: Many of the classic characters re-invented and at the same time given spring-loaded weapons
. But did this line really take off?
As for distribution, GIJoe doesn't enjoy the level of exposure in stores as it had in the 80s. I remember buying Joes in the mid-80s from sidewalk vendors in my hometown in the Philippines. Now you're lucky to find a shelf for these stuff in the toystores.
Or perhaps I'm wrong, that the world has moved on. I introduced GIJoe to my son three years ago and at first he was engrossed. But now he just turned 12 and he prefers playing the new version of Starcraft.