"You can't build a UI builder with a UI builder". :-)

I like your point about users "reacting" to an limited range of choices, explicitly stated (and surely using domain specific terminology). It's a grammar you don't have to internalize, with libraries you don't have to know about, or know the search terms to find term. It's very "discoverable", and the limited and clear range of choices minimizes the information content (increasing the probability of obtaining the desired outcome). I'm sure it would also prune the tree by omitting choice combinations that don't make sense.

I think people don't like the system guessing for you, like Office's Clippy. Maybe it's OK if the user asks for the guess - like getting a list of search results; or vim/bash completion; or suggestions (google, Stackoverflow)