@Edent A big part of it for my friends and I was accessibility.
As it slowed down it quickly got monopolised by a handful of shady providers pushing the unspoken piracy angle, and the ‘public’ ones soon dried up as the ISPs got fed up of constant DMCA takedown requests and other pressure. It also took not insignificant resources to host and as you mention, what little moderation there was also faded away.
For myself and my close circle, we were Amiga users (for our personal computers) quite far into the early 2000s, and still routinely used Usenet over BBS/IRC and other web based social platforms, simply because the client support was (mostly) better.
Even as late as 2015, the likes of BT/Plusnet etc. still hosted their own Usenet servers as a legacy hangover but eventually pulled the plug. Their documentation is still live afaik.
I’m not on the ‘bring back Usenet’ train as it’s largely run its course, but I do remember my time with it fondly.