A big part of filmmaking, and a big part of the power of filmmaking, is creating characters that people fall in love with. So, those things, like the bloopers, create more reality and dimension, and the sense that these are not drawings or shadows, but they are living, breathing, thinking characters. That's the illusion.
When we make films - even 2D films - you're always trying to create this illusion of 3D, anyway. You're trying to create a believable world with characters walking, in and out of the perspective, to create the illusion that there's a world. The desire and drive to create this illusion of three-dimensional space is something that is true about every kind of film because you want the audience to really be experiencing it, first hand. It's a natural extension of the storytelling and the process of filmmaking.
An actor uses his body as a tool and an instrument. In the same way a musician plays an instrument, the actor uses his body to convey feeling and emotion. An animator uses a pencil or a computer to create the same thing, the same exact way... An actor is taking words that are not his own, and he has to bring some kind of authentic life to those words. It's the same goal, to create this authentic life. Even if it's a drawing, or if it's a cartoon, you're still trying to create authenticity because, if the character emotes authentically, it has a power to connect with the audience.
Films are made the same today, as they've ever been made, in certain respects. The scriptwriting, the pre-production, the storyboarding, and the designing are all the same. The technique of animation has changed, in the sense that rather than drawing it by hand, we use a computer as a tool. The computer has become a pencil to draw or paint the images that we see in a film.
