Totally understand your frustration… I think plotly does a lot of things very well, but there are improvements needed on this aspect. I don’t know why either, it might be that the chart component has too many layers and functionality slowing down the animations…
That said, if you need a very customized vis with animations, one road I can suggest is to write a custom component and build it directly in javascript/D3. I’ve done it in a few internal applications in my company and “open-sourced” the approach (like in this post). Not quick or easy, but possible.
Hope this can help!