I think the optional part might have a bit to do with it. In Java, C#, Go you are 'stuck' with the garbage collector, so people learned to live with it and usually realized it's not as bad as people claim it to be.
Also parallel compilation is my absolute favorite. When I found that compiler flag and used it I was amazed at how fast code compiles with the D compiler.
I just need a project and some time to play around with it, but my first impression as someone that worked with C++ and Python in the past is really positive.
[0]: http://vibed.org/
Using an OS written in a GC enabled systems language made me realize that not only it was viable, it was quite productive to work in such environments.
The problem is having a big name OS vendor willing to push it to the nameless crowds no matter what.
So far we have to get happy with half-hearted steps like Swift, ChromeOS/Android(Things) with heavily constrained NDK, .NET/UWP on Windows and maybe in a decade with more baby steps, we are able to reach what Oberon/Topaz/Spin/Inferno/Singularity/Midori had on their design.