I like D a lot but find it's not a good fit for many things. C++, Java and Python have great tools and libraries to rely on. Not so much with D's small community. Writing wrappers and interop always feels like a hassle, so it's easier to stick with just one language.

First time I used D was before the version 2, back when there was the Tango library. D seems to have improved quite a bit since then, but it's still in the same position as before.