This essentially all boils down to “I don’t like new things, and despite it being made more secure, I don’t trust it”
How are sandboxes “untrusted crap”?
You talk about complexity being bad, yet you seem to prefer X11 over Wayland, and 500 different implementations of the same thing, implemented separately by every app developer, rather than using a standardised xdg-portal. Surely you see the contradiction there?