XML is case sensitive, then, from my point of view, disabling case folding doesn't goes against xml 1.0 specifications but the contrary, disabling case folding allow us to distiguish between diferent cases of the same letter ('a' and 'A') which of XML are two diferent things.
From my point of view, disabling case folding is a good practice and I think it should be disabled by default.
More information on:
http://www.isacat.net/2001/xml/case.htm
and
http://www.w3.org/TR/REC-xml
Thank you.