A couple animations with implications for fit and position to contemplate. In both animated gifs the riding position is identical yet pivoted forward or backward relative to the center of the bottom bracket. Notice that as the handlebar comes up the stem has to be shorter, the rider is shifted backwards, the saddle moves back and down, and there's a hell of a lot more weight on the rear wheel.

The riding position is not identical if you change the height and set back of the saddle. Seems like you would want to keep those constant if they were set correctly initially.

I like your animation. It helps visualize the effects of changes in position. After a number of years and miles I have arrived at a very comfortable position but it was a painful struggle to get here. It makes sense that a small change in position can have a major effect on comfort during a long ride but I have found that a small change can have a significant effect even on short rides. To help with those changes, I've marked, using a whiteout marker, various locations on the bike for seat post and saddle location and handle bar. This has made it easy to make changes on the fly to those locations and get back to a previous location.

More/less weight goes to the arms too. What is missing here is the power that rider is putting out. The force on the pedals is lifting for the arms. A high power low front is more comfortable than a low power low front.