I don't think that this bias is a bad thing. It's nice to read about cool technologies that you might not use in your day job. But anyone using HN to decide on the right tool for a project should carefully consider other sources of information as well.
But if you say that Common Lisp is great, there are fewer people who have really used it, so fewer people who have used it and didn't like it. And since fewer people got into it unless they really wanted to, it's easier to say "You didn't really understand it, then, or you would have liked it." The number of people who can say "No, I really got it, and I still didn't like it" is relatively small.
So far, that's just demographics. But then you get into the language itself. Java isn't an exciting language. It's not fun. It's kind of corporate and bland. There aren't many people who are really enthusiastic about Java - nor does Java give them reason to be.
GraalVM is doing some amazing things with polyglot support and native compilation.
Java's project Loom is trying to bring fibers in a really nice way to the language.
It is slowly working on bringing value types and inline types as well.
And it's got a few cool GCs being experimented on, as well as a nice foreign memory API.
Java recently got really nice improvements, multi-line strings, text blocks, local type inference, a shell, running code from source scripts and switch expressions.
Moving from OCaml to C++ or Go would be a drastic and surprising change, but it's not nearly like that.
There's some really great stuff about OCaml. I don't think we could have gotten through the first 2 years without OCaml, we repeatedly made very large scale changes to what our product was and how it worked, and that would have been 10x harder in something else.
I actually think OCaml stands to be in a great place in the next few years with the work being done by core community members. See https://twitter.com/patricoferris/status/1323330884515356672.
Also why not to choose F#/Mono (and now .NET core) for example?
I don't remember considering F#, so probably just never occurred to me.
At the same time, it's a good response when somebody muses in a saddened manner "I wish my favourite language was more popular". Then I can spring out of the bush and tell them why it isn't. This doesn't mean I expect the OSS community around the language to serve me -- of course not! But it's a good explanation on why language X isn't more commercially popular.