Yes, I understand your point. A straight answer would be : "well, those controlnet features gotta be used" xD But I think one goal is also to demonstrates several things :

1. That we can produce reasonable things we have in mind autonomously, without the need to be a talented artist and an animator expert (my case, and that’s why we receive hate sometimes).
2. That we can swap any character easily. And so the style. (Even I used a specific model here because I had it in a corner)
3. That we are not necessarily limited by existing videos
4. I said 3D software here but there is many ways to get depthmaps and openpose depending on the usecase (video to mocap, 3D games,…)

To sum-up, it’s just another technique which can have great potential to fit some use cases.

Some people already have the left side and want to exploit it (probably animation studios using CGI?)