[zokier]

The major problems are not really technical in nature. Homographs, Unicode madness (normalization etc..), and the biggest problem of all: input methods. It would be highly ironical if "international" "more global" email would lead to more nationalized islands because only local people can input those "international" email addresses. A single global character set (in the non-technical sense) is required for a system to be really global. You might argue that ASCII being that global set is eurocentric, but there isn't really any good alternatives available. Afaik pretty much every computer can input ASCII with relative ease no matter how exotic their users native script is.