I think why I’m grateful for this change is that, while the sidebar I think is designed for the users to be able to customize to their liking, I imagine 1) most users may not even know that’s possible and 2) most may stick with the defaults anyway.
I, having used Discourse for years and having a coding and website background, can struggle with the UI and customizations, so I like the ability to set the default order of the sidebar categories for users assuming they may never actually change them.