For us we support multiple platforms (win, osx, ios, android, ...) and need to interact with hardware io, codecs, and gpu apis. We could use C, I suppose, but we'd be giving up some of the niceties of C++11 such as smart pointers that make life much simpler.

That's not to say we don't have some platform-specific code in the "preferred" language (in some cases there is no choice in the matter), but most of the system is C++.