You nailed it! I am a typographer by profession, and I know exactly what you mean. The trouble with most light-markup languages is indeed their very limited document model and set of node types — basically an html subset, just good enough for blog posts, and, at best, source code documentation.

I’d rather take inspiration from something like the Chicago Manual of Style: we need many types of lists; more levels of headings/sections and control over their formatting; plates and figures; there are many types of “blockquotes”, etc. Poetry and drama are just some of the more difficult cases. How far must one go, or what, for example, should we do with things like Apollinaire’s [calligrames](http://en.wikipedia.org/wiki/Calligrammes)?

As for your use cases: Besides AsciiDoc’s “verse” and Skriv’s support for literal line breaks, z.m.l. too takes these into account. For drama, there is Fountain.io’s domain-specific light-markup for screenwriting.

Very interested in your research and software. Do have a look at my (premature draft) light-markup [concordance}(https://github.com/rhythmus/markdown-resources/blob/master/l...), and feel free to add.