[KrisAndrew]

Managers and executives often care about languages. It actually is pretty difficult to find developers who can easily pick up new languages. Most of the places I've worked at, the average number of languages known by individual developers was about 3. By the time I was 20 I had learned 13 (and 3 human languages). That's an exception.

If your programming stack consists of 3-4 different languages, the mental maintenance required by the developers can become considerable. That number of languages is an inflection point. After that point is reached, you'll see resources directed to rewriting things in order to reduce the overhead, or the executives will end up creating new departments with different language requirements and roles.

It's not that people are lazy, complacent or stupid, it's that on average they can't retain multiple representations of the same thing in their head. If you search around, I think you'll find the average number of human languages known by any given person is between 2.5 and 2.8. Programming languages are no different than human languages.