That’s true, but:
1) they did add threading macros, which are very popular, and these seem to serve a very similar purpose for transducers. You could argue their inclusion would make the language a little more uniform even.
2) There is precedence for doing the same operation with different mechanisms, like map vs mapv, so the change fits in nicely in that sense
3) as the article points out (edit: just realized you are the author, heh, hello!), transducers often have better performance than alternatives. I think it makes sense to highlight them and encourage their usage as much as possible. The more high performance code in the wild, the better. Even just introducing new ergonomics that facilitate their usage will influence that.