As long as we're hung up on details of the markup syntax, it's going to be very very hard to make useful forward motion on things that are actually going to enhance the capabilities of the system and put creative power in the hands of the users.
Forget about syntax -- what do we want to *accomplish*?
I think you got this sideways. The concrete syntax doesn't matter, but the abstract syntax does. Without a clear specification no competing parsers, no interoperability, no decoupling APIs, no independently evolving components.
(Abstract syntax here means "XML representation" or structured representation or DOM tree i.e. an abstract syntax tree. But for that you need a language i.e. Wikitext specification and an implementation of a parser as of today doesn't do the job.)
worrying about memorizing ASCII code points, it's let us go beyond fixed-width ASCII text (a monitor emulating a teletype, which was really a friendlier version of punch cards) to have things like _graphics_. Text can be in different sizes, different styles, and different languages. We can see pictures; we can draw pictures; we can use colors and shapes to create a far richer, more creative experience for the user.
GUIs didn't come about from a better, more universal way of encoding text -- Unicode came years after GUI conventions were largely standardized in practice.
In order to have a visual editor or three, combined with a plain text editor, combined with some fancy other editor we have yet to invent, you will still need that specification that tells you what a valid wiki instance is. This is the core data; only if you have a clear spec of that can you have tool and UI innovation on top of that.
Cheers, Dirk