unicode/utf-8 support out of the box
Someone I know was venting that Ello, a brand new service, could not handle UTF-8 characters in usernames. This meant no kanji based usernames. (In an interview, one of the Ello devs laughs about having to hack in support for ümlauts to support german users. That wouldn't have been an issue if the site supported UTF-8 from day 1 instead of being ascii focused).
Being UTF-8 aware out of the box also could help mitigate various security vulnerabilities that could pop up either trying to wedge support in for it later and/or people abusing the system by stuffing in UTF-8 where the backend is merely expecting ASCII.