Now this is not the same language/community improvement system that many popular projects nowadays use, but OCaml has been stewarded in its way for a few years now, and it's something the contributors feel is sustainable given the size of the project and the resources available.
About Unicode specifically, there is of course support at the library level as you mentioned (the most well-known library is Camomile), but to try to justify not including it in the language distribution itself, to a certain extent many applications just don't need it. Those that do can of course use libraries, but many (say, backend servers) don't really need to process Unicode strings, they just need to shovel bytes from point A to point B and not actually touch the contents.