I just reposted this article to comp.misc, where we've been keeping up a parallel discussion for years. Usenet doesn't have the sheer numbers it used to, but anyone still there is there because we love it. Usenet's flaws remain unmended, but its strengths remain unfettered. :)
I'm on the hunt for a good dedicated Windows NNTP reader, failing that I might have a go at writing my own (that supports text posts only - none of that dodgy binaries rubbish!).
Because Thunderbird sucks, as do other email clients that claim to also support news. As an email app it's below average, but as a newsreader it's downright horrible.
A good newsreader needs to be able to thread and block and filter and preview binaries. Few apps ever did this well, and many that did have since become obsolete (Pan2, Unison, etc).
With the rise of Windows and the decline of Usenet, the demand for newsreaders faded fast, leaving few or no supported freeware newsreaders alive today. Even commercial newsreader apps are increasingly rare.