naturalplastic wrote:
What exactly are you asking about?
Are you asking...why do they direct live action films rather drawing/creating animated cartoons because cartoons is what they aspire to do?
Are you asking why they direct short live action films as opposed to directing LONG live action films?
Are you asking why they direct rather than act, or do voice overs?
As ever, you ask the real questions, np.
Others have answered the most obvious interpretation, "why do they direct short animations?", which is that they're cheaper to produce and money is a limiting factor.
If the question is "why do they direct short live action films instead of animations?" then, assuming that is true, I imagine the answer is again about budget. Directing a short film still requires a lot of the same skills regardless of whether it is live-action or animated: framing, pacing, directing any actors, and so forth, as well as the script if you're a writer-director. Doing a short live-action film shows that you have many of the requisite skills, and I don't think Pete Docter actually does the animating anymore.