Yeah, it's fine that the encoding is not infinitely extendable. But if it didn't encode the length into the first byte, you'd have 1 extra bit for 2-byte sequences, 2 extra bits for 3-byte sequences, etc. That means that you can double the number of possible glyphs per 2-byte sequence (for an extra 2048 glyphs in the 2-byte range). For 3 bytes, it's 2 bits for an extra almost 200,000 glyphs before having to jump to 4 bytes. This would be a huge boon to East Asian languages like Chinese and Japanese.