This show is the only cartoon based on Marvel comic characters that is currently on tv. It is a great success with both ratings and fans, and has only just started its second season. Jeph Loeb feels that the story-arcs are too long and that every episode should be self-contained. The plan is to cancel ths show and start a new show with self-contained episodes that are more "kid-friendly".
The story-arc's are NOT a bad thing, when the show itself is properly written (Unlike NBC's "Heroes") and the continuity all makes sense. Like the old saying goes, "If it ain't broke, don't fix it".
A simple soultion would be to make another, more kid-friendly, cartoon such as the cancelled "Super Hero Squad". Leave the "Avengers: Earth's Mightiest Heroes" ALONE!