Can you elaborate on the issues with iTunes, Wifi, and Xcode? I know the app store is just a wrapper (which makes it pretty bad) but Xcode is a wonderful (but buggy) IDE, I don't understand how you can make WiFi bad, and I really have no idea where they went wrong with iTunes.
iTunes is a slow, bloated mess with UI that gets worse with every release. Classic dumbness: Adding 1 song or photo to a phone requires erasing the entire phone because it's synced from another computer? Or trying to sync a folder of photos from computer -> brand new iPhone with brand new iTunes doesn't work. Just stalled progress bar forever.
WiFi: There are constantly WiFI problems with OSX and iOS. From plain-ol' reliability to straight up bugs. This isn't including boring DNS stupidity from OSX.
To be fair, in the time of RealPlayer and such, QuickTime was the least bloated and best performing video player around. There really isn't a use for it in 2016, though.