I think it's a great move that Apple is cautious with including a hardcore LLM in everything. They are not that useful to the regular user.
Siri, sideloading and AI features all all the same way; give people options and nobody will complain.
Sideloading is bad for business. Most users don't care. Remember, we, the devs, are not the core target/biggest spenders. They are targeting a large audience of young people who are not tech-savvy.