Hi, I'm a C programmer. D is an okay language but it's obviously designed to improve on C++ rather than C. You might as well suggest that I use Java or Vala in my systems programming. That's not acceptable.
If someone made a language where the semantics were exactly like C (but with the addition of parametric types, and maybe a better string handling library) then I'd consider using it on my microcontrollers. Right now, not even Fortran is a good alternative to C, so I'm gonna keep using C.