I can't speak to Rust, but I suspect in the case of Haskell the criticism doesn't arise because the whole language is so foreign to people coming from C-like la

I can't speak to Rust, but I suspect in the case of Haskell the criticism doesn't arise because the whole language is so foreign to people coming from C-like languages that everything being an expression is just one of many hurdles. So it doesn't stand out as much on its own, and either you give up or by the time you make it through enough of the other hurdles you probably appreciate the expression-orientedness. I say this as a Haskell enthusiast. Do-notation probably also masks the fact that everything is an expression from newcomers a bit in the beginning.