The iTunes developers slowly destroyed it. Then, when there was a chance to save it, it becomes a front-end for Apple Music. No thank you.
Swinsian brings back the feel of classic iTunes, and it's primary focus is simply managing you music library. In the current climate of streaming services, Swinsian is targeting a niche audience. I'm in that niche, and I love it.
I've tried about ever music player and library management app for macOS and Swinsian is the one that handles all of my needs.