Of course, one-line rebuttals are not worthy. I always intended to expand upon it.
Here are two significant points to start with:
(1) There are powerful, well-used, and significant computer languages that in fact are case-insensitive. Firstly, Pascal. Then, in no particular order, Fortran, Ada, Basic (most of them), and SQL. Some SQLs even go so far as to treat the data itself in a case-insensitive manner!!
(2) Case-insensitivity is NOT a language design issue. It is a human utility issue. Languages (and file systems!) that are case sensitive are plagued with hard-to-debug errors cause not by the language, but by how hard humans actually find it is to work within case-sensitivity constraints. In fact, I would venture to say that anybody who is comfortable working in a case-sensitive computing environment has spent YEARS bending their brain into that shape, so much so that they no longer even see it as a problem, and can construct (non-human) arguments as to how it is in fact better. In case you are wondering, I am such a person, though I am now trying to at least partially undo that error from my past.
Finally, here are two links that go into some detail (some of it not so relevant, sorry) as to why case-preserving case-insensitivity is important, including replies and rebuttals and demolishing strawman arguments. Please at least peruse them:
(1) OddThinking ยป The Case for Case-Preserving, Case-Insensitivity
(2) The USS Quad Damage (which is in response to the above link)
If you look carefully, you will even see a position on the case preservation of keys explained and defended, specifically, that if an object has key/value 'FooBar:7' then searching for key 'foobar' should match it and show the matching key/value pair as 'foobar:7'. I understand that this may be difficult to implement.