Think back to when COBOL actually changed. This is when the PC was becoming more common. So people would tend to use whatever came with the PC. Basic was the most common language. If Apple and Commodore had opened up into a COBOL interpreter, it would have lasted that generation.

I am not sure why C took over from Basic. Perhaps it had something to do with speed or with control. I don't know if the same reasons would apply to Cobol.