This is too abstract for me. What exactly means "good work"? Let's say that I wrote some article, or just plan to write an article, and I ask myself -- is LW the right place to publish it?

Well, it depends on the topic, on the style of writing, and what kind of audience / reaction do I want. There are more things to consider than just "good" or "bad". Is it a Nobel price winning material? Then I send it to a prestigious scientific journal. Is it just a new idea I want feedback on? Then I guess whether I get better feedback on LW or somewhere else; again, the choices depend on topic. Something personal? I put it on my blog. Etc. Use your judgement.

It is also possible to write to a scientific journal and post a hyperlink on LW, or to write a concept on LW, collect feedback, improve the article and send it somewhere else.

Yes, if the work is optimized for LW, it is not optimized for <something else>. Different audiences require different styles. Maybe LW could have a subsection where the articles must be written using the scientific lingo (preferably in a two-column, single-spaced format), or maybe we are OK with drafts. I prefer legibility, journals prefer brevity, other people may prefer something else.