I very much disagree that it succeed at the reveal goal, of "creation being easy and fun" and I don't think it has achieved a goal of being a creative game.
When i did read your experience of getting some hand puppet animation to work, that was exactly what i have expected.
It was clear from the beginning animation would become its weakest spot. All characters looked like stick puppets on ropes. It was restricted to fun and comedy, but serious stuff seems impossible.
But that's not the problem. Even if they did much better here, the main issue remains: Making games is a lot of work, gamers don't have enough time, and it's not possible to make it easy.
To address this, it might be nice to add levels of abstraction to break out of isolated creations - most of them just shit probably.
I mean few skilled passionate guys make Trackmania, Super Mario Maker or Minecraft, and much more regular gamer people make levels or other content for that. So there is always more and enough content.
It would be nice to replace 'select creation from menu' with 'walk into creation from acommunity MMO hub in a shared 3D world' as well, with people designing their avatar for that, etc.
But this would require ability to create simplified tools like easy level editors, and also more server infrastructure.
I think we will get there... The final game, played by the whole world.
But i have no problem if it takes many years until then...