On the other hand, if Reason were such a massive improvement to OCaml syntax, where are the people clamoring for F# to adopt more of Reason's ideas?

(Admittedly, F# already shares a couple Reason ideas like C-style comments instead of OCaml's traditional ones. So the waters are clearly muddy here to begin with, but a lot of the big things like let-binding scopes and ;; versus ; presumably would be big F# requests if Reason was so strongly superior to the inherited OCaml legacy.)