Why are many languages case sensitive?
Is it simply a matter of inheritance? C++ is case-sensitive because C is, Java is case-sensitive because C++ is, etc.? Or is there a more pragmatic reason behind it?
Unix.
Unix was case sensitive, and so many programming languages developed for use on Unix were case sensitive.
Computers are not forgiving - an uppercase character is not the same thing as a lowercase character, they're entirely different. And back when processing cycles, RAM and so forth were expensive it wasn't seen as worth the effort to force compilers and computers to be "forgiving", people were just trying to get the things to work.
Notice how case insensitivity didn't really become something useful until things like Visual Basic came along - once companies started to get invested in the concept that getting the masses to program was a good thing for their bottom line (i.e., Microsoft makes more money if there're more programs on Windows) did the languages start to be friendlier and more forgiving.