I’m not sure. If given the choice in isolation, perhaps most people would be happy to sign up for the new Siri. When it’s a trade-off that requires 25 GB of storage for Apple Intelligence and sticks various unhelpful buttons on the keyboard, maybe fewer people want it.
And there is certainly also a contingent of young people (especially) who dislike generative AI on ideological/moral/environmental grounds. That group may be overrepresented online, but it does exist.
Because I’d guess nearly everyone wants the new Siri to just be there and working.