Media Type first vs Library first is flawed
For years Plex's primary categorization was libraries. To throw that out seems bizarre.
The new concept of selecting your media type first is deeply flawed for many users. For many users, the media type is secondary, unimportant, and merely a technical decision to get things to show up in their library. Plex doesn't support all media types, so I was forced to put things like Music Videos, Movie Special Features, or porn under TV or Movies when I created a library for them. I don't actually care the media type. I care about the name of the library. Now, I've got remember what technical choice I chose years ago. I can understand the "content first" approach, but I think the library-first approach needs to still be an option.
Seriously, think about that: you've directed users for years to think "libraries-first" and now you eliminate that. I find the new mechanism incredibly awkward and now I'm hunting through a UI rather than enjoying my content.