Yes, but in a world where people have been trained to ignore signs if they want to have nice things. No kid and most adults would think twice before clicking I agree even if the screen was flashing red and the phone was making klaxon sounds.
If there's any company in the world that can use UX to their advantage, it's Apple. If they can create text message social division simply through blue vs. green bubble, they can find a way to subtly make non-App Store apps unpalatable except to technical users who know what they're doing.
