I think that D is kind of like Mercurial: both less popular than some other wildly popular alternative, but we still hope that at least some of their ideas trickle back into the more popular sibling.
I absolutely agree. C++ is at least a decade behind D. Literally.
The kinds of features that eventually hit C++, D actually had for at least ten years. I think of D as a clean break. A major version upgrade with an API break. Whereas C++ has committees that move incredibly slowly, D has two architects who are decades long professionals and considered experts in their fields. It has focus, and it's not concerned with making code from the 70's compile on a modern compiler.
I simply cannot enumerate all of the features I use from D that I use every day that have become second-nature. Until I try to code in C++ again and I'm like, "The !@$@!ing order of declarations matter?! I can't make circular references without manually writing forward declarations?!" It feels like banging rocks together to make a 747.
I think that's mainly because C++ is an ISO standard used all over the world by big business and governments. So its standards are released less often and with a great deal of testing and care. I bet you will be able to specify -std=c++Whatever for the next 50 to 100 years, maybe longer.
I think that D is kind of like Mercurial: both less popular than some other wildly popular alternative, but we still hope that at least some of their ideas trickle back into the more popular sibling.