Earlier quoted context omitted.
A lot of awful software shipped under Steve Jobs. X Code has always been a buggy mess, iTunes bloated greatly under Steve (remember Ping?), iMovie '08, etc etc.
iTunes was hideous. I once tried to reverse engineer the XML that stored the library and concluded it must have been designed by a distracted intern.
https://developer.apple.com/library/mac/documentation/Cocoa/...
There are also many libraries available to decode and encode these files in various languages.
The reason why XML property lists look this way is that they were a direct translation of the older NeXT "property list" format, which was sort of like binary JSON. Dumping an alternating list of keys and values isn't pretty XML, but it ensured minimum translation headaches from the old format.