Good point Twiddle, it is new with C++11, so they might have to wait for some older compilers to age off into obsolescence. I think newer MSVC’s support it (probably >= 2013), but VS2012 still had some major holes in their C++11 support, so it might not, and there are still folks using that version.
I have noticed UE4 uses some c++11 features in the code base, like the override keyword, so they’re at least not avoiding 11 entirely.
I might take a crack at adding this on my local source base, just to TArrays, to see how that goes.
(aside: I fixed my second example above which was meant to say TArray rather than std::vector)