Yeah, Nick definitely makes a good point about the vast # of rehashes in 2004 freeing up the developmental teams to work on E3 dilligently.
A good thing to think of too is that it's the last film as far as anyone knows. Could theoretically be the line's last big push and it's likely the company's not overlooking this fact, so it may have extra umph to it. Plus whatever alterations and adjustments needed to be made after the lessons learned from the E2 line and things... It seems every film's been a "learning experience" for Hasbro as they've come and gone.