Eldee Stephens (of ThessaSOURCE) sent us a clarification as to why Mac OS Extended Format requires Text Encoding Converter extensions: "Evidently, Mac OS Extended Format uses Unicode internally for file names - hence its ability to support longer file names - but the Mac OS doesn't support Unicode directly. So, the format requires the use of Apple's Text Encoding extensions. Eventually, those services will be folded into the Mac OS and users will be able to name their files with very long file names and with all sorts of special and foreign characters. In the mean time though, those extensions are required."
Update: Larry Rosenstein notes; "Strictly speaking, support for Unicode is orthogonal to support for longer file names. Apple could have supported longer single-byte file names. But the use of Unicode for text is a long-term goal, so it makes sense for HFS to "do the right thing" and support Unicode now. Any time Unicode is involved (whether it is HFS or MRJ), Text Encoding Converter is needed to convert between thevarious Mac character sets (e.g., Mac Roman) and Unicode."
Jim Correia adds: "In fact, while the HFS supports names longer than 31 characters the OS currently does not."