In the tutorial it says: "In this tutorial we'll stick with `h` to keep it simple and close to the metal." I'm pretty sure they put that in there just to aggravate the HN crowd.
Personally, I like using `h` over JSX - JSX can be nice to read, but for people that don't know how it works behind the scenes, it makes things look like magic.
Once you know how Hyperapp works behind the scenes, it's much easier to make the decision to JSX if that's something you care about when developing. I have the same opinion about React, and other libraries that have a strong preference to JSX over their native/function implementations.