Not every app needs to deal with the enormous complexities implied by "full unicode support", and given the huge cost of that, there's a real place for a minimalist approach. If all I do with unicode is input strings from the user, store them in a database, and then later spit them out, I don't need to be able to do Turkish case-conversion, and I may not want to pay the cost of making it possible.

Certainly tools and APIs help for those cases where an app needs to do the sort of complicated text-processing that warrants "full" unicode support, but it's not at all clear that the proper place for such support is in the base language libraries. It's quite reasonable for the language implementors to say "if you want to do X, we'll support that, but if you want to do Y and Z, please use external library L."