rationale behind quotes for camel case?

Hi all,
first of all I'm not expressing any critique against the use of quotes for identifier expressed using camel case. However a lot of new postgresql users seems to be unhappy with the use of quotes for camel case identifiers, so I'd like to know what is the rationale behind it. I mean, is a feature of the partser or is a need for it to work? Anyone can point me to an explaination?

Thanks,
Luca