This could be a case study on how design at Apple has gotten worse. Take iTunes/Music for Mac:
- From Catalina on, full-height sidebars started eating into valuable toolbar real estate.
- In Tahoe, not only to stupid big corner radii eats more into you usable area, they now allow the inspector sidebars to cut even more into toolbar space.
- The volume & scrub controls are now an extra click away.
Just compare these newer UIs to #iTunes from 2010. Full-width, excellent use of space.