I would use it to create a button and keyboard shortcut to rapidly create a new tiddler from the selected text in another tiddler.
I find often that I will write some plain text in a tiddler, and later on, decide to create a tiddler about some of the words/expression I previously used (e.g. provide extra information about it). So the optimal workflow would look like select the text in the paragraph I want to turn into a new tiddler, hit a keyboard sequence, and that would 1) replace the selected text with a wikitext link, and 2) create a new tiddler with the selected text as its title.
As an example, say I create a tiddler about gizmo X, and in the tiddler, state that gizmo X is created by Company Y.
Later on, I may wish to rapidly create a Company Y tiddler. A quick way to do that would be to highlight the words “Company Y”, hit a button/keyboard shortcut, and have that turn into a link and create a new tiddler with the exact title.
Please note that I don’t rely on CamelCase auto-linking normally. I feel it would be a relatively easy problem to solve with a <<textSelection>>
core variable (but I am most certainly overlooking a few details).