What, roughly, is it that you say has changed a lot? Would it be the broadening of topics, from purely software/tech to news and political topics which software/tech has influenced, and is now enmeshed with?
I read HN for years before I signed up. In my case, I joined because I wanted to become involved in some conversations - now open to me as a potential participant rather than as a clueless but interested observer. For me, HN changed - for better or worse - in ways that included me more. My background is as a production-side journalist (sub-editor, deputy editor etc) who became fascinated by tech when, in 1994, I took an online role in a pioneering news project in the UK. After that, I combined news roles with informing the design of CMSs and other newsroom tools; I have worked with many developers. Now, I am more in project/product management of, mainly, media tools.
For me, at any rate, HN has shifted from an interesting source of tech news - what are the latest frameworks, what's happening with search/tracking/social technologies - to discussions of how these things impinge on or affect my work and life. I still enjoy reading all the way-over-my-head stuff, anything from Hubble to Ligo to quantum mechanics, though.
Is your objection to HN now vs then because you see it along the lines of the "Eternal September"[1] influx of inappropriates who in effect choked Usenet to death?
I see it differently - and, of course, I am just guessing at your objections - and enjoy my time on HN; so many subject specialists and practitioners, pioneers even, chip in across so many domains.
The success of HN for me, I suspect, hinges partly on a self-policing group of contributors and commentators, but also and even more so on some deft, even-handed and nicely judged moderation by real people.
Edited to add clarification of Eternal September: