Popular, trendy, kid friendly, in demand... doesnt mean Disneys going to have character representation in the parks. Just think of how many fan favored characters we never get to view, unless they happen to appear in a ticketed event that guests pay for. And still theres not all that many.
I remember when we began visiting WDW years ago, how many various characters we could run into as we went from park to park. Now... youre lucky if you see more than the same old cast from the last trip. My DS has an autograph book he took on trips when he was young thats filled with unique characters. Now youd never get many pages signed.