> I don't really understand why reST is so unpopular compared to Markdown.
There are two reasons: first is that Markdown is much simpler and is more narrow scoped and second is that reST implementation only exists in Python and Haskell - to some extent, not supporting extensions, obviously. Both of those reasons make entry level higher.
For HTML generation Markdown is much easier for most people to get used to and understand. When needing to provide output in various formats reST is more suited but also have a bit of a steeper learning curve.
It depends on what you're doing. For documentation I'm always running reST but for articles for sites etc (with a static site generator) I will turn to Markdown.
I second this opinion, though it's been a couple years since I last used it. Designing complex tables in reST was far more cumbersome to me than just writing it in HTML. It requires you to basically know the HTML your markup syntax will generate anyways, then deal with the quirks of that but with less overall control than raw HTML gives you.
However, generating PDFs, a static website, and any other formats from a single reST document is much easier than doing to equivalent from an HTML document so it has its uses, but I would not use it as blogging markup unless I planned on publishing a book from the same blog content.