I would think it was more because it was way simpler to adjust software. People mostly used their own software, they didn't have millions of lines of code hanging around (they probably could grep all existing source code in a few hours, if needed), the authors of any software that needed changes all were available, often in the same room, and even if the languages didn't change, they would have to update their programs because they made breaking changes to their OSes every day (that may be slightly exaggerated)
Also, what language would you switch to on your Unix installation?
Also, what language would you switch to on your Unix installation?