I'm not sure it should be Apples job to build a best-in-class text editor. I haven't used XCode in a long while, but last time I did it worked pretty well with external text editors, and you could configure the UI in a way that really facilitated using it just for just compiling/debugging.

Every single IDE I've used, I've always used another text editor for doing actual programming. It's nice to have a half-decent text editor in the IDE for debugging (see value of variables in the code, looking up and quickly fixing compile errors, etc).. but I don't expect it to be as powerful as vim, emacs, sublime, et.al.