Well hold on for a second. I LOVE iTunes. I've used it since it first came out for Windows with version 4, I was 13 Y/O at the time. I started organising all the MP3's I had collected in a 'jukebox' for the first time. This marked the birth of my music library. I was really thorough and became increasingly OCD with the metadata. I've kept at it. I used it extensively with my iPod mini, and dear God how I loved that apparatus. It was my companion like nothing else, except of course for my GF at the time. She also had an iPod and we used to swap them around from time to time, that was a lot of fun

. Anyway, we broke up after a couple of years. iTunes too entered some rough waters. Times weren't so simple anymore, apparently. Seemed to mirror my puberty. Cover flow was epic, but only there to be enjoyed for a few short years. I figured as my library was steadily growing (about 30 GB at the time?) that it wasn't really going to be cutting it for much longer anyway. There were design overhauls, many of them a bit unnecessary and some were quite terrible, and it became more buggy. Especially things like artwork and other metadata would get f*cked over with no warnings, randomly. I got my first iPhone, the 4, when it first came out. Couldn't fit my library onto it, but I'd select my favourite albums and playlist, just like I had done with my iPod. Along came iTunes Match (which is probably the most insane subscription out there that anyone can get), which made managing my library even more fun, because I could instantly upgrade all my collected mp3-files to DRM-free files in decent quality. DRM-free, so I could actually use those files to burn CD's for the car stereo, drag them onto cheap MP3-players for adventurous trips, use them in movie projects I'm doing (and I could literally go on for HOURS). But the first years with iTunes Match were horribly, the random f*cks became much worse and it almost drove me insane. But I love my music so I kept at it. It became better! The bugs seemed to fade after a few years. It's still MY library. It's one of the most precious possessions I have. It's highly personal, it's expansive, it carries so many memories. Also, iCloud music library. Another great feature, with so many bugs at first. Apple Music came along. I was SO happy that it could all be integrated in the current system I had - keeping the physical files on a SSD on my MacBook, and on a BACKUP DRIVE, as well as in the cloud ánd on my (256 GB) iPhone. Just how I like it. Even if I'm hiking in the most far away backcountry or in the mountains above reception area, or abroad or just on airplane mode, I have acces to my music library. ALWAYS. And I get the benefits of discovering new music with Apple Music, and even merge the DRM-protected Apple Music files with the DRM-free iTunes Match files I have/ keep adding.
The music app. Let's hope this'll be another form of that level of integration. Don't take away iTunes Match, and please don't take away the option to manage and sync a physical music library, EVER..
My library is about 155 GB right now. It still fits in my pocket. And even though electric cars are cool, that doesn't mean I don't prefer to ride a bicycle. Streaming has a place now and in the future, but so does possessing music. It's only data. I can afford the storage. It doesn't add mass. But I sleep a lot better with my library here with me.
Thanks for all these years of letting me build my music library Apple, now please let me keep it.