Maybe I can understand better with an actual example? I might just be biased by React's mindset, but I've always considered two-way binding (and any non-unidirectional data flow) a mistake, and it has only brought me pain and sorrow.

In other words: the patterns I use outside of Rust are also Rust's happy paths (on paper, maybe I'm just missing something?)

(For clarity: I'm talking of userland here. I assume that's what OP meant by "UX" -- I agree with your "big runtime" point, but that's why my RAM is filled by Electron apps.)