Nope. While modifying the "core" files is (still) a big no-no, the types of things you can edit in maps and standalone mod files in a "officially support capacity" is far, FAR greater.
Included in that is AI scripting. In fact, AI scripting has gotten lots more tools (much more behavior is configurable in the scripts, rather than coded into the engine). You can even override for specific units how the AI will try to micro them, and/or use spells, instead of the default management.
So yea, AI scripting now has official tooling from Blizzard for SC2. In fact, there is one such "enhanced AI" project well established for SC2, the GreenTea AI.