I’m also really tired of things that pretend to be single apps but every other thing you click on will jerk you into an entirely DIFFERENT app. Oh, a sidebar: logically, clicking any item on the side should always update the right-hand side, right? Nope: some of the items you click on might update the right-hand side (after displaying a stupid spinner of course); others will hurl you into the App Store app and slide in some un-Mac-like UI to display 3 pieces of information (usually with truncation that can’t be fixed in a view that can’t be resized); still others might just open a web page (one that only works in Safari of course, because to hell with your browser preferences).
Why is any of this crap necessary? It’s perfectly clear that Apple just doesn’t care at all anymore about making nice, smooth, usable experiences. More than that, they don’t seem to even know how their own desktop platform has traditionally behaved. But even if they did want to change how things behave, why are so many things behaving differently? It is a complete mess and they should be embarrassed. No leadership AT ALL on the UI front.