Well of course if you have the freedom to write a mathematical expression you're going to be able to present it in a way that is clearer than if you have to type monospace characters into a text editor.
I'm not sure it's realistic to expect to be able to type a mathematical expression using ascii more clearly than you can write it by hand (or implement using special unicode characters).
Quite some years back I worked with JetBrains MPS which used a "projectional editor" instead of a text editor. It was pretty neat to be able to enter "code" as mathematical expressions, or even state machine tables or flow diagrams with actual nodes instead of a text representation.
Sadly not much has happened in that space since then, but it was cool to think about what our tools of the future might look like. (of course ignoring all the practical reasons why we're probably still using regular text files in 100 years)
I'm not sure it's realistic to expect to be able to type a mathematical expression using ascii more clearly than you can write it by hand (or implement using special unicode characters).