Don't forget that F# was mostly "forked" from OCAML, while C# was mostly "forked" from Java. So yes, F# got some OCAML features, but it got the weird ML syntax as well.
F# probably is a better functional-with-OO-aspects language, but C#/Scala are clearly better OO-with-functional-aspects languages and programmers currently want the latter.
You're probably right that it feels unfamiliar to Java/C#/Scala programmers, but I enjoy the sense of security that F# and other restricting languages provide.