I wish UI designers would just leave stuff the hell alone when it works fine. System Preferences has been one of the most consistent parts of OS X/MacOS for 20 years now and I really appreciate that consistency. I know where to find stuff. Instructions and guides on the web remain relevant when new versions are released. Yes, occasionally things move around a bit and icons change, but not too much.
Mac is not iOS and it shouldn't be. I really dislike the trend of taking UI concepts that are great for a smartphone and applying them to a large display.