Early iTunes was pretty nice — a lightweight, focused music player and not much else. Over time it became slow, unusable bloatware — an iPhone/iPad backup / sync manager, an e-commerce / ad platform (iTunes store), a social media platform (Ping), a way for Apple to automatically tag/categorize/mess up your library, among others. I'm not sure if it's better now, I abandoned it years ago.
I associate iTunes with useless bloat and loss of user control. My experience has exclusively been with windows and I've never purchased a device that requires iTunes to sync. Before iTunes came out, applications like foobar/winamp/Windows Media player were already loaded fast, used low resources, stable, and performant. iTunes was not. Before iTunes, you would copy your mp3s to your device. With iTunes you had a mysterious syncing process. Stories about requiring a 3 hour sync to add one new song or your entire collection being deleted were not uncommon. There was DRM in the early days. I surely wasn't going to switch from my pre-iTunes system to a system with DRM for literally no other additional value. If I knew that advanced options were missing, I'd include that in my complaints, too.