Just a sampling of some of my favorite software or at least ones which I use frequently out of choice, along with their primary development language(s) so far as I understand things off the top of my head. These are in alphabetical order (if I don't make a mistake in manual sorting):
Bullet: C++
Chrome (including V8): C++
Eclipse: Java
Firefox: C++
Git: C
Gmail: JavaScript (front), ? (back)
Google Calendar: JavaScript (front), ? (back)
Linux: C
LLVM: C++
Skia: C++
There are probably other things I should have on that list, but it's a bit C++ (and C) heavy right now.
Maybe C++ is used because of inertia. I know it's far from ideal. It's a mess even, but it's clearly capable of being used for making good software. Something worth musing in my lifelong quest to find how I want to code.