I'm all for functionality, but git should never have been a smorgasbord of random bolt-on special cases. If you have to break the basic core functionality to make a feature work, it's not a good feature.
I never said jj was awesome. I've never used it. I'm already adept at git, enough to have opinions on its advanced features, and the knowledge to avoid them, so I'm not sure if I'd gain all that much from jj.