I know quite a few Windows users (that did not own iPods) that converted to using iTunes to manage their music library. The alternative at that point was often Winamp, and they managed to mess up the good thing they had with Winamp 3.
Overall the library functionality, as well as the Rendezvous-based library sharing (made LAN parties into interesting ways to discover new music) made for a quite sweet deal, and the Windows version truly was good.
Stuff went downhill sometime post-iPhone, when it started to become a weird one stop shop for phone sync, backups, movies etc, but even then the odd cool thing was added, like coverflow, or the fairly nice UI where the album coverart’s edge color faded into the background of the listing.
Point being, iTunes wasn’t crap from day one, it was cool before it deteriorated into that.