Just out of curiosity since it seems like a good idea to integrate the latest changes in so you don't have some 2.x users using the old version of sugercube, some using the new, and your tutorials being wonky as a result.
If you mean the latest version of SugarCube 1.x, that's because a new Twine 2 release hasn't been published in a while. The next release should include the most up-to-date version of SugarCube 1.x at the time of publication.
If you mean SugarCube 2.x, then that's for a couple of reasons.
Because SugarCube 2.x in still in beta and I've asked that it not be included until I publish, at least, a release candidate. Not that it's not perfectly usable now, but I'd rather it not be included by default until I feature freeze it.
Because Twine 2 doesn't yet support handling multiple different versions of story formats. That feature is being worked on, but it's not ready yet.
Comments
If you mean SugarCube 2.x, then that's for a couple of reasons.