The problem is that when you work on big teams and are forced to work in C++98 with lots of style guide restrictions. Or when management will ever allow for updating the compilers on the build infrastructure.
Also compiling C++ code in C++11 mode won't make many developers use Modern C++, instead of C compiled with a C++ compiler, as many still do.
Maybe it works for your context, but in a global context we need to have safer languages for systems programming. Which were already available when C didn't had any meaning outside UNIX.
That's true, but you can write C code in D as well, so switching to D won't make people write idiomatic code either. If they won't learn how to use one correctly then they won't care enough to use another correctly.
And if your company won't let you upgrade compilers, then it certainly won't let you switch languages altogether.
Also compiling C++ code in C++11 mode won't make many developers use Modern C++, instead of C compiled with a C++ compiler, as many still do.
Maybe it works for your context, but in a global context we need to have safer languages for systems programming. Which were already available when C didn't had any meaning outside UNIX.