You are looking at this in a very limited way - from your point of view. Language designers must take into account a whole other set of considerations: cultural reasons, compatibility with other languages, common coding practices etc
All modern languages use case-sensitivity: which ones don't?
As someone who used BASIC for a number of years I got very tired of developers using different cases for the same variable. This sort of thing is very tiresome to look at and encourages sloppy programming. If you can't be bothered to get the case right - what else can't you be bothered to do?
