What does the higher bar look like to you? For me, the major missing features of C# are:
* Immutable record types
* ADTs with completeness pattern matching
* Higher-kinds
F# is also missing higher kinds, but can do the others. Did you have something else in mind?
None of them makes me write prettier GUIs or better use of EF.
Actually, higher kinds could make you write more composable and reusable GUIs. I don't see why "prettier" is the only metric of interest.
Immutable records also makes it easier to share data safely, thus making scaling across cores easier in some cases, without worrying about plan interference.
The bar has moved so much on this one. I remember when C#'s wonderful lambda syntax, along with all the extension methods that LINQ added, qualified it as having pretty good functional programming support. Now that other languages have gone out and copied sane lambdas, and "Map" is in libraries left and right, C# has to keep reaching for that higher and higher bar.